i agree with striek on this one. lol. but anyhow if your looking for temp. then i have an athlon 2800+ (working at full speed thanks to striek by the way). on idle it run about 42 C.
running an athlon you will start running the risk of frying components at 55 C.
Also if your planning to overclock i agree with nihil on this one. the stock heat sink and fan for the CPU is pretty much useless.