svchost.exe

i posted this with my HJT log, but i'll post it here too. i got a couple questions about svchost.exe. i checked on another forum for more info about this process. it said there that its a normal process, however, if it takes up more memory then explorer, then the process might be "questionable". also, how many of these processes are supposed to be running? i have about 6 svchost.exe processes running. 2 from the network service, 3 from system, and 1 from local service. is this normal?

i've been told that it's normal and not to worry about it.