My G Force 7950 went south, so I had to reinstall my original G Force 8300.  Frame rate went crazy and had to lower the settings.  I would like to get another video card for this computer, keep in mind I plan on having a gaming computer built in the near future, so I don't want to do any crazy modifications to this one.
My power supply is 350 watts, and I would like to get the best I can for this system without having to resort to changing the power supply or adding additional cooling.  I went to newegg and see if I could find another 7950, but after getting bug eyed looking at all the numbers I didn't find one.  I would like to try something else anyway, just for a change.  I also noticed I have on-board sound.  I am thinking about installing a sound card.  Would this help?  Any recommendations for a video card?  Remember I'm not a computer geek, but I have installed a video card before.  Keep it simple please.
My system is a Dell XPS 410
                   Physical Processors:       1
                     Logical Processors:       2
                       Processor Vendor:       Intel(R) Corporation
                         Processor Name:       Intel(R) Core(TM)2 CPU          6600  @ 2.40GHz
                         Additional Name:       x86 Family 6 Model 15 Stepping 6
                            Popular Name:       Core 2 6600
                                Frequency:       2520 MHz