I'm running Windows 7 Ultimate RC and WindowBlinds beta 2 works fine. I didn't have to tweak anything to get it to work.
On my Start menu, there are two entries for WindowBlinds under Object Desktop. Be sure that you launch the one that says (BETA2). When I installed, clicking the icon launched the Beta 1 version -- which, for me, does not work. Also, I found that the Windows 7 compliant skins tend to work the best. I've also been able to use skins compliant with Vista & WB6 -- but not all of those work.
If you look through the threads in this forum, you'll find an older post of mine, and in there, are links to some Windows 7 skins.
Good Luck