Rouge I ONLY use AMD processors, admitdly the only machine on for long term periods is my Duron machine ... however that one is only rebooted once every few days and hasn't actually been off in almost 3months. Even then was a few hours as i tinkered with the hardware inside.
You WILL kill the lifetime of processors through overclocking, because running a processor at a speed it was never designed for will do that. However in the 3years i've had my Duron it has never failed me once, it is quicker than even the Pentium3 Equivilant (i'm talking realtime tests like Quake3, Max Rendering Times and such) and also I've not even had to replace the fan unit once, because the bearing on it are still nice and quiet.
I can't even count the time i've replaced them on the Pentiums ...
But then again i've never really had a processor burn out which wasn't my own fault, Virus's have caused it, incorrect programming has caused it... and once about 10years ago i accidentally put a friends AMD 486 DX4-100 in the wrong way, but actually that was only unusable for about 2hours as it cooled because we tried it again and it worked fine (even today)
To say AMD processors are poor because of your experience with them is just sad really, especially saying they seem to have no real usage life - because it isn't true.
I know many many people that overclock processors and then claim its the processor's fault they failed, but not being funny but Intel will die ALOT quicker being overclocked ... its only in the Pentium4 series they've places in safety measures to STOP people from trying to overclock more than 100Mhz (which is still pretty irrisponsible)
Saying it is upto continous use though just seems like crap to me, and would be no matter what manufacture you mentioned as both are extremely good at long term useage as most of the Pentium2/K6-2 series were designed specifically for business long term useage in mind.
If they are as poor as you mentioned them I know ALOT of companies which would be asking for replacements all the time and AMD would go out of business for it.
if you didnt overclock or anything, it is possible you simply bought from a bad batch - happens sometimes even from the best manufacturers.
Anata aru kowagaru no watashi! 