As dgibbs says, i7 has no benefits for gamers, I built my rig for gaming and I had to leave out an SSD as I couldn't afford it, i5 is the better choice, is more than capable of doing anything you need it do.
You'll only need an i3 for cs 1.6 lol!
3820 + 2600k are the same price, pretty much same benchmarks too, so not really a big deal whatever you go for there, if your wanting s2011 then go for that, but bearing in mind the prices of cpu's are quite high £440-800 etc.
I have a set of these:
and they do the job very nicely, best headset i've ever owned and look the bees knees too!