I would not buy a 9800GT, it's just not as good as other cards at that price. It's also over kill for what you want to do, with those requirements you could probably buy a 30-40 dollar card and be fine.
What slots do you have available on your motherboard and how many watts is your power supply? What store would you prefer to pick it up at (you've really go a choice between Best Buy and Fry's here, maybe Radioshack for some really cheap cards)? What sort of output do you want (VGA, DVI, or HDMI)? We can probably find you one at best buy that meets your requirements and parts at best buy are really not much more than ordering them online. Best buy makes their money by selling geek squad warranties, overpriced phone accessories, and $100 hdmi cables, their parts are not that expensive and I actually picked up a case at best buy for less than what newegg was selling the case for. It was an antec 300 and I think it was on sale for like 49.99 or something.