Yeah, I'm also curious.

I did this for Windows update on Vista last year. It was really misbehaving, chewing up a lot of memory and CPU time. Eventually I found and applied a patch but during the investigation, I isolated Windows update to its own service executable container.

TL; DR:

   sc config <servicename> type= { own | share }

I got that from this SuperUser stackexchange question:

http://superuser.com/questions/860117/isolate-hosted-service...

A registry-tweaking approach is also given.

Then wrote up my own answer to the WU issue:

http://superuser.com/questions/77658/svchost-eating-up-memor...

Excellent, thanks! I wonder if someone could create a VBS script to make all services "own". And, another problem, I wonder if Windows allows to rename processes, like e.g. Linux can because I don't want to see 50 svchost.exe in the task manager - I want them named after respective DLLs.