How would I update my graphics card for my Desktop?

Hi, I really want to upgrade my desktop to play some games. Currently I have Windows XP Service Pack 3, Intel(R) Celeron(R) CPU, 440 & 200GHz, and 0.99 GB of RAM. My computer model is a eMachines. I really would like some professional answers because I'm in need of help so I can get the right parts for my computer. I want to play the latest games, so just tell me what Graphics Card could handle that.