Is it so wrong to seed your GUID?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CustomGuidTest
{
    class Program
    {
        static void Main(string[] args)
        {
            Guid customGuid = GenerateCustomGuid();
            Console.WriteLine(customGuid.ToString("B"));
            Console.ReadKey();
        }

        static Guid GenerateCustomGuid()
        {
            Guid result;
 
            //0xFACEB00C
            //backwards, but required this to achieve desired result.
            byte[] custom = new byte[] { 0x0C, 0xB0, 0xCE, 0xFA  }; 
            byte[] random = Guid.NewGuid().ToByteArray();
            byte[] final = new byte[16];
            for (int idx = 0; idx <16; idx++)
            {
                switch (idx)
                {
                    case 0:
                    case 1:
                    case 2:
                    case 3:
                        final[idx] = custom[idx];
                        break;
                    default:
                        final[idx] = random[idx];
                        break;
                }
            }
            result = new Guid(final);
            return result;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page 
{
    static OrderedDictionary dictionary = new OrderedDictionary();

    protected void Page_Load(object sender, EventArgs e)
    {
        
        //the opportunity here is to allow the users to set their favorite aliases
        if (dictionary.Count == 0)
        {
            dictionary.Add("0", "0");
            dictionary.Add("1", "1");
            dictionary.Add("2", "2");
            dictionary.Add("3", "3");
            dictionary.Add("4", "4");
            dictionary.Add("5", "5");
            dictionary.Add("6", "6");
            dictionary.Add("7", "7");
            dictionary.Add("8", "8");
            dictionary.Add("9", "9");
            dictionary.Add("a", "A");
            dictionary.Add("b", "B");
            dictionary.Add("c", "C");
            dictionary.Add("d", "D");
            dictionary.Add("e", "E");
            dictionary.Add("f", "F");
            dictionary.Add("g", "6");
            dictionary.Add("h", "4");
            dictionary.Add("i", "1");
            dictionary.Add("j", "9");
            dictionary.Add("k", "7");
            dictionary.Add("l", "1");
            dictionary.Add("m", "3");
            dictionary.Add("n", "2");
            dictionary.Add("o", "0");
            dictionary.Add("p", "7");
            dictionary.Add("q", "9");
            dictionary.Add("r", "2");
            dictionary.Add("s", "5");
            dictionary.Add("t", "7");
            dictionary.Add("u", "4");
            dictionary.Add("v", "7");
            dictionary.Add("w", "7");
            dictionary.Add("x", "7");
            dictionary.Add("y", "4");
            dictionary.Add("z", "2");
        }
    }
    protected void Button1_Click(object sender, EventArgs ea)
    {
        Byte[] use = getTimeInSeconds();
        DisplayGuid.Text = GenerateCustomGuid(use).ToString();
    }

    private static Byte[] getTimeInSeconds()
    {
        TimeSpan span = DateTime.Now.ToUniversalTime().Subtract(new DateTime(1970, 4, 9, 10, 32, 0));
        double seconds = span.TotalSeconds;
        Byte[] byt = BitConverter.GetBytes(seconds);
        Byte[] use = new Byte[8];
        for (int it = 0; it < 7; it++)
        {
            use[it] = byt[7 - it];
        }
        return use;
    }

    private string getCharacter(string text, Guid guid, int idx)
    {
        string tempValue = "";
        object o = dictionary[text.ToLower()];

        if(o != null){
            tempValue = o.ToString();
        }
        
        if (string.IsNullOrEmpty(tempValue))
        {

            tempValue = guid.ToString().Substring(idx, 1);
            if (string.IsNullOrEmpty(tempValue) || tempValue == "-" || tempValue == "{" || tempValue =="}")
            {
                //random works terribly bad
                Random random = new Random();
                int randomNumber = random.Next(dictionary.Count - 1);
                tempValue = dictionary[randomNumber].ToString();
            }
        }

        return tempValue;

    }

    private Guid GenerateCustomGuid(byte[] use)
    {
        Guid result;
        Guid randomGuid = Guid.NewGuid();
        
        string part1 = TextBox1.Text.PadRight(8, '*');
        string part2 = TextBox2.Text.PadRight(4, '*');
        string part3 = TextBox3.Text.PadRight(4, '*');
        string sum = "".PadRight(16,'*');
        if (part1 + part2 + part3 == sum)
            return randomGuid;

        byte[] random = Guid.NewGuid().ToByteArray();
        byte[] final = new byte[16];
        for (int idx = 0; idx < 16; idx++)
        {
            switch (idx)
            {
                case 0:
                case 1:
                case 2:
                case 3:
                    final[idx] = Convert.ToByte(Int32.Parse(getCharacter(part1.Substring(6 - idx * 2, 1), randomGuid, idx) + getCharacter(part1.Substring(7 - idx * 2, 1), randomGuid, idx+1), System.Globalization.NumberStyles.HexNumber)); 
                    break;
                case 4:
                case 5:
                    final[idx] = Convert.ToByte(Int32.Parse(getCharacter(part2.Substring(10 - idx * 2, 1), randomGuid, idx) + getCharacter(part2.Substring(11 - idx * 2, 1), randomGuid, idx+1), System.Globalization.NumberStyles.HexNumber));
                    break;
                case 6:
                case 7:
                    final[idx] = Convert.ToByte(Int32.Parse(getCharacter(part3.Substring(14 - idx * 2, 1), randomGuid, idx) + getCharacter(part3.Substring(15 - idx * 2, 1), randomGuid, idx+1), System.Globalization.NumberStyles.HexNumber));
                    break;
                case 8:
                case 9:
                case 10:
                case 11:
                case 12:
                case 13:
                case 14:
                case 15:
                    final[idx] = use[idx-8];
                    break;
                default:
                    final[idx] = random[idx];
                    break;
            }
        }
        result = new Guid(final);
        return result;
    }
}

}

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <style type="text/css">
    .textbox
    {
        width:100%;
        border:0;
        font-weight:bold;
        font-size:22px;
        overflow:hidden;
    }
    </style>

</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:TextBox ID="TextBox1" runat="server" MaxLength="8"></asp:TextBox> - 
        <asp:TextBox ID="TextBox2" runat="server" MaxLength="4"></asp:TextBox> -
        <asp:TextBox ID="TextBox3" runat="server" MaxLength="4"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" Text="Create Guid" 
            onclick="Button1_Click" /><br />
        <asp:TextBox ID="DisplayGuid" runat="server" CssClass="textbox" ></asp:TextBox>
        <asp:Label ID="Label1" runat="server"></asp:Label>
    </div>
    </form>
        <script type="text/javascript">
            if (document.getElementById('<%= DisplayGuid.ClientID %>').value != "")
            {
                document.getElementById('<%= DisplayGuid.ClientID %>').select();
                CopyToClipboard('<%= DisplayGuid.ClientID %>');

            }

function CopyToClipboard(controlId) 
{ 
    var control = document.getElementById(controlId); 

    if (control == null)
    {
        alert('ERROR – control not found – ' + controlId); 
    }
    else
    { 
        //determine the value of the control
        var controlValue = control.value; 

        //copy to clipboard 
        window.clipboardData.setData('Text', controlValue);
        alert('Copied GUID, ' + controlValue + ', to the clipboard.'); 
    }
} 

    </script>
</body>
</html>