I currently use the Gigabyte P35 DS3L, although if you want more options the DS3R is a very nice option.
For Powersupples, here is a nice list
Tiered PSU Listings - Tom's Wiki
Video Card, I wouldn't bother with the 8600. Either go with the 3850 or 8800GT (256mb versions), if you want video playback acceleration etc..
RAM - A lot of descent brands out there. With RAM being so cheap it might be worth getting 4gb to futureproof your system, but somewhat worthless if you are just loading up Windows XP. 2GB is the staple amount atm.
I agree with Zol about the cpu fan.. unless you plan to OC your Q6600 up to 3.2ghz+, I wouldn't worry.
Jam it back in, in the dark.