Just upgraded to sp2. I'm using the AMD-64 processor (but running standard 32-bit WinXP home)... and all works fine (WindowFX, WindowBlinds, CursorXP, BootSkin, Logon Studio, etc.)
(Although I did have to disable DEP to stop the computer from crashing due to WindowBlinds being perceived as a virus/trojan by SP2's DEP).
If you have problems, uninstall via the ADD/REMOVE control panel, the make sure the entire folder is deleted off your harddrive. Reboot & re-install.