You need to hack explorer.exe to change the XP start button, but it is kind of an important file, so make a backup before you start.
Open Windows Explorer and locate explorer.exe in your c:\windows directory. Make a copy of the file in the same directory and name it explorer.bak.
Now for the fun part. Run the Resource Hacker: Choose File, then Open, and open c:windows\explorer.exe. Skate on over to String Table>37>1033, where you should see "start." Change this to whatever you want.
Click on the button labeled "Compile Script." Now go to file, and click Save As. Save the file as Explorer_new.exe. You can't save it as Explorer.exe because Explorer.exe is currently in use. Close all programs and restart your system.
Boot to safe mode with command prompt (F8 on startup).
Log on as an administrator.
Type "copy c:\windows\explorer_new.exe c:\windows\explorer.exe" (without quotations), then type "yes" (again without quotations), then close the command prompt by typing "exit" (by now you should know not to type the quotations).
ohh yea, i forgot, i heard that if u were runin anything but xp it could only be change to something that was 5 letters but im not sure so tell me if u find out different, but i know for sure that if ur runin xp it can be bigger than 5