Is this good for gaming?

hp pavilion a807w is the computer model from 2005 the specs is amd athlon 64 processor 3200+ 2.21 ghz has 2 gb ram my graphics card sucks its a winfast a340 has 128mb when i play 2d games it lags i want to play counterstrike on this computer i dont even know if its a dual core or single core might be single since its 5 years old umm is the cpu and hz and the ram good enough for Cs and i just need a graphics card to run it better? or do i need a new computer i just want to play age of empires or WOW do i need a graphic card or new computer i dont want to buy a new computer is buying a better card work like a 512mb or 1g if so what kind of card is good for cheap thank you