Gaming MOBO Recommendations

Greetings, I was building a new gaming computer. With the help of fellow forum members(thank you SO MUCH) I have narrowed my specs down to

E6750 CPU
x1950 PRO GPU

Now my question is what is a solid mobo with good stability, performance, OC, upgradability. Also what are the best brands? Gigabyte and ..? (I won't really need raid, SLI, nor integrated graphics)

Also, are basically all ram choices similar? Any point in getting DDR3 vs DDR2? Any recommendations for games like Counterstrike source?

I wasn't going to upgrade my case and 450w PSU, but any good reliable value cases/PSU's out there?

Also, anything else I"m missing? I have an audigy z2, any need to upgrade the soundcard?

Best Regards,
Thank you all so much!

Thank you so much maziar, what are the difference between the mother boards you listed above? are gigabyte the best? or asus? or abit?

DS3R has ICH9R, DS3L is DS3 "lite" so is a despecced DS3 (worse sound codec, fewer SATA)

if you don't need firewire, RAID, SLI etc. abit's IP35-E is a very good contender.