How to manage network with AD remotely including virus removal & monitoring

I asked this question previously inside a different security subject but this time to have its own question. I'm looking for a tool or application either open source or built in windows server to manage a small network or workstations & windows server in a domain environment.

The AD is windows 2003 & the clients are win XP and I'd like to find a network management application to manage & monitor the network and deploy software & patches including virus removal & scanning specially if there is a worm virus that affects all the PCs in the network.

Regards,