I love my i7 920. I have mine paired with a gtx260 and it just eats alive any game out right now.
make sure the case you get has plenty of room in it. I got a small Lian Li and now have to cut out the top of the case to add two ventilation fans.
gtx260 + i7 920 = small furnace.
Smooth is definitely right on about the sound card. You may not have it in your budget to get one right now but do it. I had never had a sound card in my life and bout one a few months back and love it. Not only does it sound better than onboard but it takes some of the load off.
Did you mention in a previous thread that you couldn't overclock your 920 much?
You might just need a better CPU cooler or maybe you didn't fasten the heatsink properly.
Heat shouldn't be much of a problem with overclocking a 920 to 3.4ghz or below.
Although an overclocked I7 can run pretty hot, it's designed to run stably at high temps.
Likewise, the 260 GTX has a pretty high tolerance for heat so <100 degres celsisus shouldn't make it crash.
I only use air cooling with my 4ghz I7 and 2 295 GTXes and a 9800 GT. Heat hasn't been an issue even though my case is quite small, like I mentioned before.