SLI or Crossfire on win7

So, i'm looking to build a new system as my current is quite old. My current card is a ATI radeon 3600HD 512mb agp so pretty much any new pcie card would be an improvement. Im trying to keep expandability in mind because I don't upgrade too often and i'm a broke student so spending $1200 every 3 months on the newest isn't an option. The motherboard im looking at is Asus P6T Motherboard - at TigerDirect.com

Which brand offers better performance for dual gps?
Are there any problems with those cards are win7 currently?
What I've heard is that crossfire is more flexible with the cards you can use together but would this really matter if im going to buy the 2nd a month or 2 after the first?

Well currently I have yet been able to get my 2 9800gt's to run in SLI in win7, and as far as I know neither has anybldy else. If someone reads this and says I'm running nvidia in sli please let me know what you did. As far a ATI I wouldn't know.

I have mine running in 7 but I have ATI, sorry.

I tell ya I have teid so many different things and then I read on a forum that windows isn't going tosupport SLi in seven but I just can't belive that, wish I would have kept the htttp of the forum. fabe

Both SLI and CF should run just fine on windows 7, Vista, and XP. What it comes down to is personal preference. I like nvidia drivers a little more and they are faster to release dual card profiles for new games. I also like the whole physx thing.
Just pick up the cards you like the most and you should have no problems running two of them.

I have used only a few ATI cards, mostly NVIDIA.
I can tell you tho I would prefer NVIDIA, because they release Beta & WHQL driver updates far faster than ATI, plus like Zahl said, they get on the ball with Dual card profiles for newer games soon after they come out.

Just my .02

sorry for the long reply time. I guess ill be looking into getting a nvidia card and once i have the money for a 2nd sli should be all fixed.