a constant 15-29% is insanely high. if you just leave it what does to hover around? right now my desktop which is running Aim, Steam, and Ie is using between 0 and 4% of the cpu.

something to keep in mind, most laptops have a power save feature which will turn the cpu down to conserve power. so its likely that whatever program you have running on your computer taking up 48-65% of the cpu is being knocked back a bit by the fact that the computer is going into a power save type more.