well, you should definitely try a new heatsink and/or some new case fans.
my thoroughbred 2400+ dropped from 56C to 46C after I installed a few case fans a Thermaltake Volcano 10+. i also installed a few more case fans and it is one quiet (and cool mofo)
if you have space, go for a Volcano 12 or Silent Boost. if you don't have space on the motherboard (like me...using a 60x67 heatsink), then go with the Volcano 10+. it is definitely worth the money.