Oh god, you have integrated graphics. Yeah, you better get a graphics card then if you plan on playing any games.
As for the type of card, anything will pretty much work as long as it is compatible with your machine. You could buy a cheap ass ATI Radeon 4000/5000 series card off of ebay for $20 and it will work nicely. You aren't exactly running bleeding edge games, so there's no reason to break the bank, you know?