Not sure I understand all this anti SLI but oh well..
SLI is a good choice if you have brought a single card say 1-2 years ago and can get your hands on a very cheap replica.
However the sums dont add up if you are going for SLI right from the off.
To answer you question though, I would go for the 7600 GT however there are some good deals to be had with ebay sales of 7800 based cards.
AMD 4200+ X2 OC 2.3Ghz
Club Nvidia 7800 GTX 256megs OC 540/1350
Asus A832n Delux MB
40 gig WD Raptor
300 gig WD Sata 2
3dmark2005 = 8652