and as far as this subject goes, unless you say my age (17) and just plainly don't have the funds for SLI285's *cough* I would go that route, or just one for now (as in a single GTX285 is still a beast) and maybe by time you'll want a second the GT3xx will have something to float your boat.
To nVidia's claims of "twice as fast"...
although that'd be friggin awesome I'm gonna say mahhh
usually just hype as it happens everytime a new "hot" architecture or revision is about to be released, I must say though on paper both teams offerings are looking pretty d@*m good atm
you guys have to realise he wants to be upgrade proof he has an nvidia board clearly. so going nvidia allows sli later on. he cant do xfire later on if he chose to.
I was simply seconding someone else's suggestion to go for a 4890 instead, they are an overall better card. He could always crossfire these too if he wanted to later on since he will be getting his i7.