I went the cheaper route by buying a Phenom II x2 550 and coupled it with a Gigabyte GA-MA785GM-US2H motherboard and a Zalman CNPS9500 air cooler that I sniped on eBay for under 30. I was able to unlock the other 2 cores so I now have a Phenom II x4 (the Gigabyte motherboard says it's a B50 4 core cpu). I've been running this on Windows 7 for over 3 months now with zero problems. I also have been experimenting with the unlocked multiplier and by increasing the cpu voltage a little I have had it up to 3.7Ghz and have decided to leave it at 3.6 Ghz for the long term. So far it stays very cool. I have run extended load tests with the Intel Burn test v2.3 utility (yes it runs on the Phenom II just fine) and Prime 95 to find out what the max temps are at 100% load on 4 cores at 3.6 GHz and they are well within acceptable levels at under 65°c and idle is under 40°c (usually 32° to 35°). even overclocked and with all 4 cores Windows 7 still works the B50 ... err 550 Cool-n-Quiet so the multiplier is dropped down and the cpu idles at about 1.1 GHz to conserve power so all is well. Yes, yes, I know that this is not a guaranteed sure thing on a successful operation of all 4 cores but so far it hasn't hiccuped or BSOD'd or done anything but run Windows 7 fast and smooth. I don't do any gaming on this computer so maybe I would need to throttle down a bit for stability but this beats the higher price of a Phenom II 955 or 965 so I'm very happy with this configuration.