A PC World reader asked the Answer Line forum about the six or seven svchost.exe processes that turn up in Task Manager.
There's really nothing to worry about here. It's perfectly normal to have multiple svchost processes running at a time. smax013, when answering antohne's question, noted that he was "running 12 at the moment."
Svchost.exe, also known as the generic host process, is a standard part of Windows. It's not something you have to worry about or interact with directly--other programs use svchost to carry out certain tasks that they would otherwise have to do themselves.
Might one or more of those svhost processes be running malware? It's possible, but there's no reason to think it likely. The fact that your PC is running multiple svchost processes should in no way raise your suspicions. But a scan with a good anti-malware program or two (see What Free Security Programs Can Protect My PC?) might calm your fears.