How many fans do you have in total?
eg: Mine has (other than CPU, GPU, and PSU), 4 fans - 2 in the front and 2 on the back. P4 2.8Ghz which is very slightly overclocked, and runs (on a cool day) at about 40'C idle or doing really simple stuff. When I run games normally goes to about 50'C, except for FS2002 which takes it all the way up to 60'C. At the moment it is running particularly hot though, as the weather is warm, so I have taken the sides off.
Also when did you ntoice it running at that temp?