My good friend Neobond told me of this... Stardock has been certified for Windows XP, Home and Pro as well as windows 2000 and Windows 98. (its not even released yet - but oh well)
Stardock have basically been certified for UNRELEASED software, and the latest beta is currently only available for Object Desktop users. It"s certified BEFORE its final release in so many words! (w00t?)
Update!
WindowBlinds for Windows XP (v3 RC1) Cheers Brad for this exclusive update, RC1 adds a ton of performance features including hyperpaint, fixes a lot of bugs, and has been Microsoft certified to work with Windows XP and previous (supported) versions of Windows.
Object Desktop users will be able to download the Enhanced version which gives you these additional features.