Rather, grab an HD5770. The 9500GT is not a gaming card, and SLI'ing them was quite pointless (no offense). An HD5770 will outperform your current setup, and the GTS250.
The computer was purchased from Cyberpower, Inc. as configured and I was more interested in pricing than components. It wasn't until after I bought the computer that I realized that the 9500 card was pretty much useless and that SLI was really not much help with the kind of games that I play. On the other hand, my son is getting old enough that he might prefer the first-person shooters and other similar games that need a more powerful graphics solution.
Since my motherboard does not support Crossfire with ATI products, perhaps I would be better off saving up and purchasing one of the higher end single-card solutions, such as the 5850, which on most performance reviews is better than the 5770 in crossfire mode. At $310 it would be the same as two 5770's cost-wise.