Well My two man computers still use a 9800 GT and a 9600GSO, both have overclocked well for me. As far as buying one off eBay, just select buy it now, no auctions then just like buying from a store. All auctions on eBay require PayPal too pay, its safe and its even owned by eBay so if there's a problem they can work together well to resolve it. You just sign up for PayPal add either a credit/debit or your bank account number for purchasing. When you buy the product, it will say pay now with PayPal you will be redirected to PayPal log in, confirm the payment and your done, its really quit easy, if you do a auction style and win, you pay the same way, most auctioneers give the winner 3 days after the auction ends to pay. But as cliffordcooley said the entire nvidia 9 series is pretty outdated, for gaming though since most games are designed to run on the even older console graphics there still ok, new cards will give you more performance while using less power, and can use dx11.