Those temps sound ok.
Some mobos and monitoring programs don't read the bios values the same, so the readings may not always be the same. Also, when in the bios, the cpu is 100% loaded so that isn't an idle reading. WinXP and Linux send halt commands to the cpu at idle, and that will significantly lower cpu temps.
My A64 3200 reads 52Cish under load with the best air cooling solution on the market and it runs just fine like that, so either my temps are off or your numbers are ok, or maybe both

If your cpu temps exceed 56C under load, you might want to consider a better heatsink or a higher airflow (louder) cpu fan.
FWIW, my aux temp is probably a sensor between my memory sticks and it reads pretty high when running memory intensive programs. Fortunately my heatsink sticks out over the mem sticks so I get a little cooling that way.