I just read this article (it's in Dutch but you can still read the graphs) and it's basically saying that you get a little bit more performance out of 2 GTX460's in SLI than a stand alone GTX480 and that if you were considering the GTX480 you should really look into the option of 2 GTX460's. It's also a little bit cheaper. Now I have 2 8800GT's in SLI and I never ran into any serious problems (only that they are noisy).

Maybe I'll stick to 4 gig of ram then, but I do make custom maps and levels in the Cry-Engine and that always takes up lots of memory (I can't always make what I want now because of memory shortage). Plus I like to use crazy texture mods.

 And its personal preference but 8 gigs of ram is a waste, I'd stick to 4gigs its more than enough to max all games at 1920x1200 AAmax AFmax.

If you want future proofing you get 1 GTX 480, and down the road in a few years when the single card isn't enough you SLI that. Currently you are already at the peak of what your system can do without buying a whole new set of cards. Also by the time that a single 480 isn't enough, they will be down in price. But whatever floats your boat.

CPU - Fine, but you may want to look at the AMD six-cores (1055T and 1090T) if you're doing any work that can take advantage of it.

Motherboard - Do you absolutely need an SLI board? Only Nvidia chipsets are dead as a family and I wouldn't expect BIOS updates. That is, if you want to upgrade to Bulldozer CPUs next year.

Graphics - WAIT UNTIL OCTOBER FOR SOUTHERN ISLANDS. But if you can't, then GTX 460 SLI is fine, though saying that causes me physical pain as an AMD fan.

RAM - You seriously don't need 8GB. It's a complete waste. Go for 4GB.

What resolution monitor are you running?

Also games probably won't breach the 4GB barrier for a while given a lot of PCs will be stuck at 3GB or less due to the limits of 32 bit Windows, FYI.

I do video and photo editing, but I'm expecting that more and more the GPU will be able to take over all those tasks, maybe I'm a bit too optimistic??

I'm not looking to upgrade my CPU next year or anything else for that matter, I just basically buy a new PC every 2-3 years. Although the pace it's going now I might upgrade slower in the future. 

I'm pretty much set on GTX460, The way I see it the Southern Islands won't be a hell of a lot faster, the thing which they can score big on is bang for your buck. I'm not an fan of either just buy whatever seems to suit me best at the moment, Although I do like the Nvidia partnerships.

Will take the advice of 4 gigs of ram.

Understood man, if you've had SLI and you like it i say go for it. A buddy of mine let me build his computer and i talked him into the dual card solution, it was fast but it suffered from microshuttering(on x2 cards dont know about single sli cards). Microshuttering is the biggest reason i always stick with a single gpu but it doesnt bother some. As far as ram goes it is your choice but 4gigs of DRR3 1600 or higher should be plenty for anyjob, dont shoot me for asking this but you are running an OS that supports that much ram right? I knew guys installing 6 gig of ram when xp only used 3.5.

If you want future proofing you get 1 GTX 480, and down the road in a few years when the single card isn't enough you SLI that. Currently you are already at the peak of what your system can do without buying a whole new set of cards. Also by the time that a single 480 isn't enough, they will be down in price. But whatever floats your boat.