There is a reason OCZ is having to cut their RAM prices. They dont seem to work at the rated specs. I made the mistake of buying some and it has been a PITA trying to get and keep my system stable. Have to play with the RAM for a week or two every time I decide to try a different OC to get it stable again.
You will get better gaming performance for the same price dropping to an Athlon II x3 and bumping the GPU up to a 460 or even a 5830.
Furthermore, I don't believe there are ANY games that utilize all 4 cores ATM.
GTA4 is the only major title I am aware of that really benefits.
If you just need a PSU then the Antec Neo Eco line (520W or 620W), Antec Earthwatts, Corsair or the OCZ Fatal1ty line would be good PSUs. The OCZ modstream/speedstream line is made by a different manufacturer and is not as good quality.