It's a good card. Personally I would be tempted to spend an extra $10-20 dollars to get the 9800 because it does offer a few goodies like running the NVidia 3-D. Obviously you could also make a case for every card up to the 9800 GTx+ with 1GB RAM which is faster than a 9800 GT SLI.
It all depends on your budget and expectations. I do recommend that you spend a moment at Toms Hardware http://www.tomshardware.com/charts/gaming-graphics-charts-q3-2008/benchmarks,30.html
You will likely be able to select the game you are interested in and your monitor resolution and see exactly what frame rate to expect. The guide to the "Best" graphic card is also useful ib giving comparisons at different price points.