the computer says gateway DX series , intel premium dual core inside, graphics my nvidia . il try doing what you said.

You said its the DX series, but I need the model number.

system model : DX4720-03

Ah, thats it. Plenty of RAM, plenty of processor speed. Your graphics is what is limiting you. You have integrated graphics with extremely limited capabilities. Only have 300W to work with, so Id recommend the following card.

http://www.newegg.com/Product/Product.aspx?Item=N82E16814130390

Installing graphics cards is pretty self explainitory. However, Id recommend doing a few google searches or watching some youtube videos if youve never messed with computer stuff.

If you wanna grab a bigger power supply, that would broaden your possibilities. You cant get much better than this without running out of power, and this card is OK. Itll play Left 4 Dead a lot better than you got, but its hardly top of the line.

:O