svchost.exe consumes CPU and Memory - Memory Leak?

My system performance is degrading day by day. It is getting slower. I found in Task Manager that a single svchost.ext is consuming a high amount of cpu. When I try to end it, nothing happens. The process appears back again on it sown. The system is working extremely. I went on web and searched about this .exe file, but found that it is some windows process. There can be virus also. How can find which service is eating my system output and what are the ways available to fix it.

There is a application available called as hijackthis. This app can give you detail output on the type of process running in your system. On that basis you can simply improve your system performance. It can be virus also. Scan your system in safe mode. But if nothing works then you will need to format your system. Installing XP back from scratch will improve the performance to great extent.