Each svchost.exe contains(runs) a group of services that Windows needs or is using.
It is perfectly normal. At the moment I have 12 instances of it running in my task manager, and that's with minimal processes running. As far as I know, trying to stop one of them can't be done via "End Task". I always wondered avout this back in the early days of XP, but after learning what it does, I don't even think about it anymore. It takes up a good chunk of memory,yes, but that's what the memory is there for.
From my understanding, the more that is running in Windows, the more svchost's you're likely to see. The only time i've ever seen it become an issue is in the case of a virus, but problems would be more noticeable then I imagine(never had it,so not sure). Also, if for some reason one or more was using 100% of the CPU, then there may be a deeper problem somewhere.
I'm sure someone here knows more and can explain it better than me, but IMO, it's nothing to worry about.