You need a new PC, that processor is much too slow to consider upgrading any one part.

AMD Athlon II X4 620 Quad Core
Would this help me ? i'm thinking to buy it :|
So
AMD Athlon II X4 620 Quad Core
Ge Force 7500 gtx 512mb
350GB Hd
Thats what i'm thinking to get
but i need a Motherboard...

hm i will look up teh cpu
and and the card u whant is not worth it the 7 series is not good try to get from 9600 and up u can get a GTX 240 DDR5 for under 180$ thats a 3.4Ghz(3 400 Mhz) mem speed (fucken fast) a game will play with out a lag

and try to get a motherboard with a min os 4 ram slots (so u can have space to upgrade ram if u whant)

and 2min graphics card slot
so if u need a new card (old 1 is getting crappy) u can upgrade and use sli mode so u use the new 1 and the old 1 (will save u money)

and ya u will need cooling cuz the pc get HOT rly HOT
if but all the parts u need buy some fans it dont cool mutch but help and if u have mony left buy a cpu cooler

or watercooler but will cost ya