Right now you have an integrated graphics chip on your motherboard, not a separate card which would mean greater power. In effect, this is basically \"not having\" a graphics card. Most such chipsets cannot handle intensive 3D games, as they are made for lighter applications. The good news is that it\'s fairly easy to upgrade yourself (I do believe though that fiddling inside a case of your machine may break some warranties, so there are risks) - all you\'d need is a good graphics card, which aren\'t too expensive these days, and knowledge on proper installation :) Luckily we have the internet, which can be a good source for both of these. Newegg.com is a great source for various system parts, and you can usually find a Geforce or ATI card for under $100, or just a tiny bit more. Aim for one with 128MB or above.
You\'ve a decent processor and a good amount of RAM, but I doubt you would have much of a pleasant gaming experience - the graphics are bound to be a bit weird, sadly.