No, 15 isn't that odd. 12 or more is the example given in the article you linked and it tells you in there how to reduce them. That said, the one that's taking up memory is probably the one governing things you're actually using. Ultimately, if you're having memory problems, a better solution would be to get more memory…
15 is a pretty normal number if you want to reduce the amount of ones going and the memory they use you should run "services.msc" and stop the one that aren't useful. svchost is just the host application for all your services to run in. currently my comp has 12 svchost services running and 57 services and i run windows7…