Krasher, are you comparing one single cored nvidia gpu against two dual cored ati gpus?
Stop drinking the nvidia koolaide Krasher and step into the 21st century. Even the modern nvidia shit (namely fermi) is double shit (unless you have a nuclear reactor for power, and liquid nitrogen for cooling).
Watt for watt, ATI pwns Nvidia.
Aside from that, its hardly fair to compare 5970 against gtx 280. Again, let me reiterate: dual core gpu of a 5970 gpu, vs single core gtx 280. Even overclocked, a gtx 280 cannot come close to ONE 5970, let alone a crossfire 5970 masterpiece.
GTFO, go read some benchmarks.