How do I troubleshoot high 'svchost.exe' usage in Windows 7?

I'm having a problem with Windows 7 64-bit. I thought it was slow and all, but then I saw that the CPU usage was always around 80% and started searching for a solution.

There are two svchost.exe's consuming around 30% each and in the resources monitor there's a system interrupts consuming 45% all the time. I tried closing the applications, but it makes no difference.

I tried some other things that I've found on Google, like disable system updates, but it didn't work.

I don't know if it will help but here's my specifications:

Core 2 Duo 4400
ATI Radeon 4850
4 GB DDR2 RAM

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EDIT

I ran the suggested program and got this information; did I get it right?

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EDIT

As you asked here it is, did I get it right now? The other TCP/IP there's nothing.

EDIT

I ran msconfig and took the services that one of the svchost.exe processes was using out of the startup and now my CPU is around 50%, but I still would like to improve it further. I can't lose that much CPU power just because of Windows...

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EDIT

Yeah, there's nothing I can do here. I am going to reinstall Windows XP soon, it's really weird...