Possible Virus That is not detecting

On my computer there is a file that I have a feeling is a virus. The file is called "svchost.exe", yet it does not quite act as the "Mimail" virus' (it does not even detect from the specific scanners. The file is in "%windir%\system32\" and in task manager it comes up four times under the user names: Local Service, Network service, System and System.
The thing that I would like to know is whether this is a sytem file or a virus and if so what is it and how can I remove it.

 

http://support.microsoft.com/?kbid=314056