Win 7 RC 64-bit here, a Q6600 with an Intel G31 chipset and 4GB RAM. It flies. Ableton is fairly solid, as are the drivers for my Phase 22 soundcard (really want to change this for an Audiofire though). Ableton has one issue though, with 7.0.16 at least the GUI has trouble updating - priority issues I think. I don't get glitchy audio, but the GUI is certainly less smooth than under XP. Responsive, but a low frame rate.