ShoXDX has created a project on CodePlex in c# to show you what each SvcHost.exe task is executing. What is the SvcHost exactly? It is a generic host porcess name for services that run DLLs. Since multiple Svchost are executed running different things, it can be hard to track down what exact actually is executing. SysInternals also has a very power program that does just this, however ShoXDX's is done in c# and is open source!
Check out his svchost viewer application over at CodePlex.