I have Win 7 Beta on my Dell Mini 9 Hackintosh (dual boot). Win 7 screams.

I even ran Win 7 on Virtual Box on my Macbook, with the Win 7 file on an external HDD. Win 7 ran faster than my native WinXP T42 Thinkpad. WAY faster than Parallels 4.0. I have a copy of RC that I may try this on.

I haven't run RC yet on my Hackintosh because I figured I'd just wait for the retail release in October. I don't want to install all my apps and then reinstall in a few months. For me, it's a definite buy because I found it to be very good. However, it'll take me some time to get used to the GUI since it's so different from XP and OSX.