I found this in a few different places around the 'net - hopefully it's helpful:

Use the Ultimate Configuration Tool (Professional Edition Only)

One of the most full featured Windows XP configuration tools available is hidden right there in your system, but most people don't even know it exists. It's called the Local Group Policy Editor, or gpedit for short.

To invoke this editor:

• Select Start and then Run, then type the following:
  
  gpedit.msc

After you hit Enter, you'll be greeted by gpedit, which lets you modify virtually every feature in Windows XP without having to resort to regedit.