I just got a new hard drive and reinstalled windows xp and now the taskmanager has the cpu usage always above 50%. My computer runs dramatically slower than it did before. Ive run msconfig and shutdown all nonessential items at startup as well as checking taskmanager to make sure nothing is running in the background. If anyone has any help for me i would appreciate it.

Dell dimension 4550

2.66 ghz 512mb ram

windows xp