Advice please!!

My new duron 1200 with coolermaster DP5-6I11A rated to 1.733ghz fan is idling at 55 deg C !!
The case is a short tower with the mother board behind the power supply - a 300w suntek with variable speed fan and the case had a fan at the bottom blowing in. Everything inside is reasonably tidy and the temps used to be fine with my k6-2 at 600.

My main worry is that this temp is way too high - especially for idle! and what I can do to lower it.

what sort of temps should i be experiancing and will i be damaging the chip at this sort of temp