So I've been sitting on the sidelines, looking at all of the benchmarks and discussions on the GTX260, GTX280, 9800 series, and 4870s.
At this point, pending optimized benchmarks for the newest cards, I've come to the conclusion that I should be fine with my 8800 GTS 640 SLI setup for another 6 months to a year.
I've got a little extra cash, but I'm thinking my money would be better spent on a large storage drive at this point. What do you guys think?

Well, g80 8800gts 640mb, even though old, is still about as good as 9600gt. In sli, performance should still be pretty decent. You might as well wait a little more, if not skiping the latest generation, at least wait until prices drop a little. Cards are expensive at launch.
http://en.expreview.com/2008/04/02 [...] p/?page=10

Dude, how about some facts. What does the rest of your system look like? What res do you game at? What types of games do you play? We know NOTHING about your setup, other then the 8800GTS SLI setup. Give us some info, and we make some suggestions.

All in his profile

I think you got a very decent system unless you want to keep into high-end gaming. Both Nvidia and ATI are commited to 6 months release schedule so by the time 2 generations goes by, you only have to wait 6 month (if you count the current releases as 1 gen). I think the next big step would probably Nehalem of whatever AMD can throw in to compete.

I to am running 640g80 in sli, I say if it owns crysis than you have no problems. By the way, overclock the gts just a little and watch it run away from the other cards. In its overclocked state it will take a smaller performance hit in high resolutions with all filters on than the bandwith deprived g92 cards, like the 9800gtx and 8800gt. 9600gt is no compaison to an overclocked 640gts

I would definitely get a bigger hard drive and maybe another 2gigs of ram but other than that you should be good for at least another 6 months.

What res do you play at, and what games do you play?

I also agree, for the most part, your set. I'd get 2x2GBs for ram (sell your old stuff.) and a larger harddrive. As long as your game play is ok right now of course...

Wow, thanks for all the replies and sorry for the lack of info.
Right now I'm into Mass Effect, replaying Bioshock, and Supreme Commander. I'm playing everything at 1440x960, max AA/AF. Both GPUs are at 576Mhz.
I'm hoping my system will sustain me through Brother's in Arms: Hell's Highway, Alan Wake, Starcraft 2, and Dragon Age.
So from what all of you are saying, I should go for the 2X2GB, larger hard drive, and do a full upgrade with Nehalem?

The 4gb ram is a must.

Consider hdd upgrade if you need the space. Get larger hdd, not faster hdd. SSD is in freefall stage of price drop, and will be affordable fairly soon. It's far faster than the best 15k rpm hdds, but won't be nearly as big. The ideal setup would be a small SSD to run OS and a few frequently used programs on, matched by a 1TB hdd for mass storage.

Your q6600@3.4ghz can still hold its ground for a few more years. No reason to upgrade to Nehalem when it first comes out. A quad core q6600 does stand a chance against octo core Nehalem on multithreaded future applications/games, although a dual would be sunk.

uh question... why do you have a SLI setup at a resolution of 1440 by 900?

I have a single 8800 GTS 640 at 1920 by 1200 and that plays every single game I throw at it at max with max AA and AF...

except for Crysis...

I'd invest the money in a good 24 inch monitor

Okay, I guess I'll go 2X2GB 4-4-4-12 and give my current 2X1GB to my wife.
Then a 500GB-1TB secondary storage. Wow, I hadn't checked solid state drives in a couple of months and I'm amazed at the price drop, thanks for the info Dagger!

I definitely don't want to upgrade my processor anytime soon, so I'm glad to hear that I shouldn't have to run out and buy a new processor when Nehalem comes out. I'd feel like the power of my current quad would be neglected if I had to put it into my kid's or wife's computer, that is unless there is some insane version of bejeweled or the sims pet stories I don't know about.

Thogrom, you're totally right about the SLI and 1440x900. But once every couple of weeks I bring my PC downstairs to play around with my flat panel at 19x12. I picked up the second 8800 from a friend for $120 because he absolutely had to have a G92 8800 as soon as they came out. Those rare 8 hour game sprees on the flat panel help me justify my purchase

Also, how many times has each of us had to add "Except for Crysis" to a post about games we can run at max res?

This is why I was curious about what games and what res you play at. You seem to play mostly RPGs and RTS games, not so many FPS games. RPGs and RTS games don't really require high frame rates, so upgrading the video cards isn't such a big deal. RTS games, Supreme Commander especially, do like lots of ram for all those units. And if you are gaming at 1440x900, I really don't see the reason to upgrade the cards.

Go for the ram and harddrive. It won't wow your socks off, but it might help.

http://www.anandtech.com/video/showdoc.aspx?i=3341
I'd agree with you about your SLI set up, spend your money in another area.