Question : How Can I Remove The Virus From My Network?

I'm the System Adminitrator of some educational institute, I've setup of 100 PC's of Network and they're all infected by viruses i've ran Antivirus Software but they come again! Such as "My-Wife,w32-Pirate, etc etc" now i'm totaly helpless so i need your help, How can get the rid of from this virus and tell me the nice way for cleanup these viruses so that it wouldn't come again.

Answer : How Can I Remove The Virus From My Network?

First you need to have Client Server Anti virus program like
Trend Micro Office Client

Next
Update your Ghost image after installing the Antivirus Program and updating your Windows firewall settings.
Then re-ghost every machine, using multi-cast.

by this you will come up with a clean solution.
or else you will endup with a traces of virus which will spread again.(these days the Viruses are more intelligent

regards
Naren