Need help with gaming build..i have this so far

mobo
ASUS M4A79T Deluxe AM3 DDR3 AMD 790FX ATX AMD

cpu
AMD Phenom II X3 720 2.8GHz

gpu
radeon hd4890 (which manufacturer should i get?)

case
antec 300

psu:
antec ea650

as of right now, i can get a combo deal of the mobo/cpu and case/psu deal at newegg for a discounted price...so i will most likely be sticking with these...

i just need help on which ram to purchase, need a good reliable ddr3 ram ...

also, does the amd phenom come with a stock heatsink, and with thermal paste, or do i need to buy those separatelY?casenb