The 680i's are nice if you know what you're getting into and are prepared
I have my E6600 at 430 fsb, 7 multiplier for 3ghz, with the ram at 1000mhz and it runs great. I tried messing with 500fsb, but it didn't work the first few attempts and I haven't messed with it since.
After dealing with some cooling issues, I got mine to about 35-38 idle and hovering 50-60 at full load depending on whether I'm running orthos, playing games, etc.
I'm getting an aftermarket northbridge cooler today so that should drop temps again some and I will probably go for 3.2 or 3.4 ghz.
If you can spend the money I would just go for an 8800 right now, whether the gtx or gts. I was going to do an sli 7900gt setup and get a dx10 card next year. But 2 7900gt's is 400-450 bucks, which I could have gotten a 8800gts for and it would have beaten the sli'ed 7900gt's. I just went all out and got the gtx and I definately don't regret it.