If you aren't sure about what to do, consider researching for a crash course to overclocking. It can literally boost your system more than 20% in speed. I have a 1.8ghz Celeron and i got it working to 2.2ghz with just the stock cooler. This can be great for people that don't have the budget for an expensive rig but having to tweak them to get free computing power.
Don't worry much about the bills, the Speedstep technology for intel processors would downclock your processor while idle.
