Overclocked CPUs don't last nearly as long as do ones running at the listed speed.
The performance gain from moderate overclocking is also so low it's not worth the trouble and severe overclocking will have severe impact on the service life of your system (cutting it down from years to months depending on how severe your overclocking is).

Also keep in mind that many AMDs leave the factory overclocked already! They're sold as suitable for a higher clockspeed than what Intel does, and as a result run hotter than do Intel CPUs of the same listed frequency.

Not as such. All CPUs are different, and so overclocking will have different effects depending on the CPU. Granted, overclocking increases heat output and also reduces the lifetime, but in many cases the end result is only 2 or 3 years instead of 5 or 6, and then you need to ask yourself this: will you really hold on to the CPU for that long?

Even so, you undertake any overclocking at your own risk.

Bleh? The days of toasty AMD processors are long dead (for now at least!). You might find Intel has taken over in that regard.

well is 54-56 celcius at full load at long hours bad?

It could be the Volcano 12, but with my beefy Swiftech cooler, I'm running 40-42C under load. I'm using AS 5 thermal paste, and a 92MM fan on the heatsink, so I might not be the best gauge. So, it could be cooler, but it's still well within the acceptable temperature range.

I am keying this on an old Celeron2 300mh - I overclocked it to 450 mh in 98 and it is still running fine (I do keep the case cover off now and take it outside to give it a b.j. with one of the cans of air). If you pay attention to power and temp., you should be able to run oc-ed continuously. If you need some reassurance go to http://forums.overclockersclub.com/ and ask there.

Amd says that their proc's can run up to 70 C, at 70 they shut down for safety, but 56 should be fine. I had an old 2100 that ran from the factory at 64C i have a 3400 amd 64 oc'd to 2.69 and i run at 56C under full load gaming, but it should be fine.