Im overclocking my AMD XP 2500+ to 2070 mhz right now, and its pretty much 49 idle and 54 load, with stock fan and heat sink, and then one front and one back case fan.
But 50's isnt too hot, although personally I usually worry if its idling about 58-59, and constantly going up into the 60's, but thats just because my setup shouldnt be doing that.