i think the tiebreaker is on your motherboard really...if you have an nvidia mobo you might as well get the GTS 250 if that fits your budget, if you're on an intel/amd mobo (and you are considering multigpu) then snag the ati 4850....
also, remember the GTS 250 doesnt do tri-SLI from what ive heard....
I think he's trying to say if you want to SLI, go with an nForce board...which is really a given, and has no real bearing on this story, lol. The point of this is the huge price drop for a card better than the 9800GTX+.