well, if your an overclocker, id go with the E8500. those things can really scream if you have the right mobo for it.
although, im sure if you wanted to, you could really push that Q9550. tough choice m8.
quad cores do offer more though and that would futureproof ur rig as well
I don't think I've ever had a cpu die on me. Did you burn it out w/ massive overclcock? Did it explode like that one on youtube? that would be cool. hehheh.
You might regret not getting the quad core a couple years down the road as more threaded apps come available.
I haven't had a CPU die on me since I tried to over clock a K6-2 way too far on a spare parts rig. Good thing I didn't do it on the K6-2 I was using for my primary rig at the time ^_^. I've seen people kill old Duron and Athlon chips from not placing on the heat sink right and either overheating them or cracking the core. Did you fry it on an overclock?
As far the Q6600, I'm not 100% certain about how it failed. My motherboard recently died, which I had replaced. Everything worked for about 3 hours, then I couldn't get the thing to post for the life of me. I tested everything extensively, swapping just about every part with the exception of the CPU and it still will not post/boot. I've checked the placement of the CPU etc and it all looks correct. As such, I'm concluding its the CPU.