To be honest the best bang for buck processor you can get is still the q6600, it has a high multi and can easily clock to 4ghz on a strong water loop. Its a 65nm quad. you need to pay a fair bit more to get a 45nm quad with the same multi, and thus are more FSB hungry - but if you running at stock speeds none of this really matter! 45nm processors have better clock for clock efficiency.
The best thing about phenom II's is they dont have a coldbug, you can cool down to -200 and they will still boot, where as intel chips you need to control the temp sometimes as high as -50 before you boot, and normally dont really go any lower than -120. Doesnt really matter if you not sticking it under a cascade or LN2.
Check out websites like
www.benchtec.co.uk or
www.xtremesystems.com these are overclocking and benchmarking forums, which are full of loads of useful information with regards to CPUs.
I have a q6600 running at 4ghz in one pc and a e8500 running at 5ghz. I prefer gaming on the duel core purely becusae of the MHZ and the lack of multi core usage.
I7's run hot, are expensive, but do have 8 logical cores, running from 4 physical cores, which means they have 8threads - they also have a built in memory controller and run triple channel memory - which means ddr3 is 3 stick sets, as 3gb, 6gb etc etc. This means the memory side of the platform is far superior to anything else, and does make a huge difference. I was playing around with a 965 extreme processor on a Rampage II Extreme last weekend and the performance blew me away.