9800 is 2 generations old, its a nice card but its showing its grays. Like mag said how cheap is your cheap, my recomendations would be 160$ for a 5770 or 200 for the 460(best price/performance is here) Both are dx11 so should last you a good 3/4 years before it stops maxing out everything on the market
and perry unless you have ever changed the PSU you will need a new one, prefabs always come with the cheapest parts possible and sell them for a premium (making your own gets you much much better parts and is much cheaper)