Window 7

Quartus works fine as long as you F8 on system start and disable driver signing checks. Otherwise Quartus still runs, but w/o USB Blaster. At least with 9.0, 9.1 and 9.1sp1. Haven't checked on 9.1sp2 yet since hitting F8 in the morning when I turn my computer on has become routine.

I have been using Quartus II on Win7 for two months now. The only crashes of Quartus I encountered are Altera home mades and can usually easily be rectified by deleting the database folders of the project folder you're working in.

Haven't tried, but supposedly you're able to sign your Blaster drivers manually or use pretty old x64 ones from Quartus 7.

Again, apart from the driver signing thing with x64 (applies to Vista x64 also), where Windows doesn't load unsigned drivers unless explicitly told so on bootup (F8), Quartus works as good as on any other rig with older Windows versions.

p.s.: I don't need to run Quartus as Administrator. It doesn't help with the driver signing anyways, because those are dropped at system start already, it seems.