What do you do that needs that many threads? I'm asking seriously. Not picking a fight.
I got it for two reasons:
1) The Opteron 180 was showing its age sitting next to my dual Xeon 5310 server. It was becoming a real pain to copy work over to it, run it, then copy it back. The Core i7 920 allowed me to complete approximately the same amount of work without involving my server.
2) Saints Row II--it doesn't run smooth without at least a tri-core and this is becoming a trend across most games
If I'm not programming, I'm probably playing games. Both can make extensive use of multithreading. In fact, all programs I write that are multithread capable will make all 8 logical cores run at 100%. Network Tool 2 doing the Internet Scan and WCG/BOINC PPD Estimator (1 &2) are an example of this as is that counter application I sent you some time ago did. I couldn't effectively write those programs on a single core and the more cores there are, the more likely thread collisions are to occur making them easier to catch and properly handle.
If my Opteron 180 system dies, it will probably be replaced by Phenom II innards because AMD is cheaper and nothing more demanding than Borderlands is run on that computer.