It varies with game, sure.
Mass Effect (1280x1024, 0xAA, Trilinear, Ultra Quality)
7950 GT: 24.10
8600 GT: 26.50
Assassin's Creed (1280x1024, 0xAA, Trilinear, max. Quality)
7950 GT: 18.90
8600 GT: 18.50
Half-Life 2 Episode 2 (1280x1024, 0xAA, Trilinear, Very High Quality)
7950 GT: 69.00
8600 GT: 55.80
Half-Life 2 Episode 2 (1280x1024, 4xAA, 8xAF, Very High Quality)
7950 GT: 51.60
8600 GT: 42.60
Crysis 1.21 (1280x1024, 0xAA, Trilinear, High Quality)
7950 GT: 6.90
7950 GT
SLI: 9.90
8600 GT: 10.40
Sum of FPS Benchmarks 1280x1024
7950 GT: 274.30
8600 GT: 235.50
So, for almost the same speed, just above
one-third the price is great.
Also,
Quote: "What's it going to take to show you? You should know that it's the second number of the card (yours, 6, mine, 9), that refers to speed."
Yes, and 7 and 8 refer to series. You can't compare directly cross-series based on the second number.
EDIT:
Another factor: mine is overclocked. It achieves almost-GTS speed.
Windows Vista Home Premium Intel Pentium Dual-Core 1.6 Ghz 1GB DDR2 RAM GeForce 8600GT Twin Turbo