Regardless of system spec, you may not want upgrade just yet. It might be best to wait a few weeks for the GTX 275's release. Perhaps even another week or two after that to let the market prices settle a bit. We might see some price reductions, rebates, and software bundles kick in on cards in the ~$175 to ~$250 range when the dust from the 4890 and 275 hitting shelves (e-tailer shelves more specifically) finally settles. It may turn out that in those few weeks of waiting you manage to save enough green to get one of these more expensive cards for even greater performance gains. That is, provided they're a proper fit for your system... Your specs would help determine that.
soryy I went out of town, here's my system spec.
2 quad core proc. 6600 2.40 GHz , 1066MHz FSB, 2x 4MB cache, BTX5-slot nvidia 680i MB.
I play games like warhammer, it can get a little laggy when there's 50 or more peeps fighting in the same zone, so I was hoping that maybe one of the newer video cards might help