svchost.exe is system process which HOSTS many different system services. Thanks to svchost.exe you can use your computer. If you try to kill svchost.exe it can shutdown or crash your computer...it depends which service is running inside.
Some malwares uses name svchost.exe to cloak yourself in the system. Just check the directory where the svchost.exe is located. If it's in windows system32 directory then it's ok.
Sometimes is not easy to analyze all svchost.exe manually, but you can use freeware tool System Explorer or any other to do this task for you.
For more information about the svchost.exe I recommend check this page http://systemexplorer.net/file-database/file/svchost-exe