I personally prefer GeForce-cards, they have better signal quality and better colors compared to ATIs cards which I saw looked a bit washed.
I have ordered the 17alu and I'm glad it has a nVidia card in it.
/ filipp
P.S. Apart from that, I think all ATI hardware sucks in general, I have not seen a single ATI-card (on PC) without artifact or drivers problems. On other hand, nVidias cards work perfect in most situations. But that's my opinion.