What does resetting the SMC do and will it harm my Macbook?

I installed Lion a few week ago, and i think its going a bit crazy.

According to iSat pro, the temp of the CPU is 48 degrees C and the fans are going at 2001 rpm. Does this sound normal? Nothing major is taking up the CPU its about 90+ % when idle. But I was wondering if resetting the SMC will stop it from getting so hot? And if i do, will it clear anything?? Thanks 🙂

sorry if i sound a bit vague, any questions I'll answer!

I have a white macbook uni-body mid 2010