You need to get yourself an after market h/s and fan,like was mentioned above a thermaltake.
Use some Artic Silver5 thermal paste instead of the supplied paste.
Increase case fan quantity and/or rpm(fan controllers are handy for this).
And get some canned air to help clean the inside of your case.
I have a xpm2500 running @ 2605Mhz (2.6gig) and my temps are around 30-40 degs but mine is watercooled which makes a big difference.