Firstly anything less than 512mb ddr 400 is NOT recommended for gaming.
Secondly,depending upon the kind of gaming you do,the type og gpu you should go for.
Let RAM be constant , 512mb ddr 400 hynix,3.5k(take or give 300 bucks)
INTEL
2.8lga+915=14-16k(In remaining money get gpu-but for anything less than 12k you won't find a good one and below 8k you will find absolute crap)
AMD
amd 2800 64 +mobo=12k
5k for as gooda gpu-best deal for u(ifeel)
For hardcore gaming of latest games,min gpu:
geforce 6200/6600/6800 series
geforce fx 5700/5800/5900 series
radeon 9700/9800/x800/x600/x700 series
rather take cpu+ram+mb for 18k and save for gpu