Skip the second 7800 GT and sell your old one, in the end you could afford a X1900 XT - which is much better than the 7950 GT, and for cheaper.
The 7900 GTO is a good option, too...
Got quite a few recommendation on the 7900GTO. What's good about it? I've heard that's it's essentially a underclocked GTX card. If true, easy to overclocked it back to GTX speed?
You can look at it two ways:
1( Underclocked 7900GTX
2( 7900GT at stock speed with 7900GTX cooling
Both ways are right, and it's a great card for the money, providing that you're willing to overclock it for maximum performance. If you don't want to overclock, then I suggest going for the 256MB X1900XT, which is available for ~240.
But i do believe that the GTO is neither a GTX or a GT as i'm pretty sure i read somewhere it has different (slower) memory modules than the GTX (can't reach as high clock speeds) and different (faster) memory modules than the GT.
I'm probably wrong, but there ya go.