Unlike previous versions of Windows, you are not limited to 5 characters on the start button. The process is, however, a tad harder than it used to be. In the Windows of yore (95, 98, Me), all you had to do was download a hex editor and use it to translate your new message into a hexadecimal code to enter into the registry.
The alternative was to download a small piece of freeware from any number of sources that would perform the hex editing and registry hack all at once. You can find links to all those instructions at the end of the article. If you have Windows XP, hold onto your boot disk, download something called Resource Hacker and read on.
You need to hack explorer.exe to change the XP start button, but it is kind of an important file, so lets make a backup before we 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:windowsexplorer.exe. Skate on over to String Table>37>1033, where you should see "Start." Change this to whatever you want. Get creative. Get offensive. Go crazy -- it's all about choice.
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, then type yes, then close the command prompt by typing exit.