The start button icon is found in the file user.exe in your windows\system directory. You can easly edit it. You need to change the 16X16 icon image in user.exe to your own. It can be done easly by using any icon editor.

1.Backup user.exe.
2.Load your icon to icon editor.
3.Copy your icon into clipboard.
4.You can't edit user.exe while Windows active so copy user.exe to some temporary folder for edit.
5.Load user.exe to the icon edior.
6.Select 16X16 image size.
7.Paste your icon.
8.Now quit Windows, and replace user.exe.
9.Start Windows

Change The Text In The Start button:

Open c:\windows\explorer.exe with a hex editor. Search for "Start" in hexadecimal format, possibly with 00 separating each character. Once replaced, reboot the system, and the new text will be there. Do not add more than 5 characters!

Move The Start button: Start moving

Thats it!