Having just set up a Windows 7 computer, I went to download the latest install file for one of my favorite Photoshop plug-ins, "Virtual Photographer" and read that it was compatible for
versions of CS4 and previous http://forums.steves-digicams.com/general-discussion/190043-virtualphotographer-windows-7-a.html
Did a little more surfing and found this explanation of how to install on
Windows 7 (although some people reporting having no difficulty).
I followed the directions and it works fine in 32 bit mode - haven't tried 64
It's really worth a look - huge variety of effects and control over them. http://www.optikvervelabs.com/