Scanned with Avast, detected 130 .dll files in the windows folder that are infected, should I delete them all?

I recently downloaded Avast antivirus 4.0 home edition to my laptop and did a scan as windows was starting up. The scan detected 130 something .dll files in the C:\Windows\System32 folder that are infected by various malware and viruses. I know very little about the innerworkings of the laptop but I am aware that files that have the .dll extensions might belong to the registry and deleting them could be detrimental. So for now, I ignored all the files that Avast detected (did not move, quarantine or delete any of them) just to be on the safe side. But then again the obvious question is what is the point of installing Avast on my laptop if I cannot delete any of these infected files, even though they might be crucial registry files? Is there any way I could get rid of these infected System32 files without having to resort to using system restore/system recovery CD? And what if I delete a .dll file and find out later that system restore couldn't restore it? System32 is irking me to no end right now. Please help!

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