If you are going to keep that cpu then I would recommend gettingt eh 4830 and saving $70. You should also be able to find some good gskill DDR2 800 (2x2gb) for about $39. I can't help with the PSU or the mobo since I always thought AMD cpu's were just an urban myth.
My best advice would be what I recommended above and then switch the mobo to a P43/45 and get an e7200 cpu for $120. The savings on the RAM and gpu is almost enough to pay for that.
FYI, the 4830 is enough to run just about anything - except crysis which has been relegated to being used solely as a benchmarking tool - on high settings if you are at 1680x1050 or below.
this is almost my exact set up. same RAM, but i have a visiontek 4850 and a biostar 790gx mobo. I'd go with a 790gx in case you want to upgrade to a phenom II in the future. Also you might want to get a beefier PSU in case you upgrade to multiple gpu's.