GTX 260 vs. HD 4870

I am assembling a machine for a friend. Which graphics card you think will give the best performance? About the same price:

NVIDIA GeForce GTX 260 (Core 216)
or
Radeon HD4870 512MB DDR5 PCI-E

I would say gtx 260 because it has more RAM.

With 2 cores, I would say that the Radeon 4870 X2 2GB is clearly the best.
Benchmarks have shown that the performance becomes better and better the more overclocked CPU (reaching 4ghz and had to stop there, but it rose steadily)

That is then Radeon with their drivers, it is something else.

Forget it, think it will be an i7 920 with 2 x GTX 260 (core 216) in. So forget the topic.
Anyways, appreciate your reply.