This isn't a big deal, but I'm dual-booting Vista (32-bit) and Win7, and Calibre won't install on Win7. The installer shows up in the process list, but never really starts.
Not sure if that's a priority for you (or even matters at all), but if I can do anything to help test it out, I'd be willing to. I know Win7's a beta and all, but just in case you wanted a tester...
Thanks and keep up the great work!!