Don't want to overload the poll or anything, but of course "Microsoft Security Essentials" virus protection would be common for Win7 users. But then again, I use that and have not had a CTD in 0.3.x at all so perhaps its unrelated.
I've got a feeling that ATI might be a factor here, from what people have posted in the past. Thanks for the poll so we can finally see things for sure!
And Merf is right... but it could still point to what is more "crashy", ie. more sucsceptible to rigging type bugs. I've played against Novacats for hours (and sometimes in them) and have had no issues with my setup.