No, not unless just leaving it on 24/7 can be considered stressing it. It already puts out enough heat to significantly warm the room it's in; I'd hate to see what it would do if I actually had it crunching numbers while idle. Could probably turn off my heat pump for the winter! I prefer power-saving to number-crunching.

My rig is probably overkill for what little I do with it, but I plan for it to last me a good long time. Putting Windows 7 Ultimate x64 on it as soon as I find some free time, and when SLC SSDs come down in price, I'll move the OS to a RAID 0 SSD array. Completely unnecessary--no rational justification for it whatsoever--but that's never stopped me before.

Whereas in the past, a rig could be outdated 6 months after it was built, nowadays it seems that CPU technology has peaked, at least in terms of performance. CPU manufacturers now focus on making their chips more efficient, stuffing more cores into them, or adding features. I figure it will be a good long while before eight 3.2GHz cores aren't enough to do anything I want... as long as the magic smoke stays in the computer.