Windows XP Service Pack 3 - REQUIRED

IMPORTANT: Windows XP Users: Version 8.8.x and up REQUIRES Windows XP SP3 (service pack 3) to be installed. To check if you have this installed, right-click My Computer and choose Properties. If you are using Windows XP and don't have SP3 installed, go to and install all updates for your computer. CMS will not function correctly without SP3.

If you're using Windows 2000, you should install Microsoft Core XML Services (MSXML) 6.0.
If you're using Windows Vista, you don't have to be concerned about this at all.