I have been intensely trouble shooting my system for a 2 weeks. Initially I thought it was the video card, now the RAM is giving me trouble but replacement RAM did not fix the problem. Here are my older posts pursuing RAM and video card help.
I have used the asrock p45ts-r board with both ddr2 and ddr3 slots. It ran pretty well, but I didn't try any overclocking. The only issue is that windows 7 didn't find the lan port driver, but using the motherboard cd fixed that. Another board that looks promising is the xfx as9 hdmi for only $69.99 shipped.
I had my computer diagnosed at the local shop and it turned out to be my mobo which lost it's ability to interact properly with my RAM over time... I don't know how this happened.
I went with a ASUS P5Q Pro turbo because it was on sale. Also looked long and hard at the Gigabyte EP45 UD3P. Both had a $20 rebate, gigabyte was more expensive.
I wanted X-fire and RAID options. I also heard I wouldn't have to reformat with the same P45 chipset. Well in the end I am reformatting... I decided RAID looked like too much trouble with my multiboot but the mobo has a handy hardware RAID 0 or 1 I can set up later, probably for keeping my data safe. I do not think my power supply can even handle X-fire so I should have kept things simpler, but hey, I get a rebate.