iStat Pro

iStat Pro is a very nice -and Free- Widget App that let you know what's going on.
From CPU to Memory, Battery Health, Hard Drive, Temp, Fan Speed, etc.
Highly configurable, it's a real pleasure. (nice design too)
So, don't worry & fear no more: It has my blessing: Download it!
http://www.islayer.com/apps/istatpro