Before doing the following try a selective startup to make sure it is not a 3rd party server via msconfig

• load taskmanager with the svchost = %100 issue
• load services Snapin / Control Panel
• disable/stop each service until the memory/cpu usage is normal

Additonal

• svchost viewer can be used to narrow down candidates, but just going throught he list alphabetical is easier
• try windows update first (automatic updates), this can also be npoted that when you stop the offending svchost its starts later again on its own
• There is an app that seperates out the child processes of svchost
• there is a registry setting to force all svchost child process to run individually