Nimda messed up my Windows Installer

Just joined this workplace, found Nimda on a new Dell running Windows 2000 Server. Got all the virus off, got protected, but still have residual probs. Is there any way to restore my Windows Installer without re-installing Server? It comes up with and error, it can't start! Looking at the log it doesn't seem to be there or just may not have permission to run. I've tried to reconfigure Installer to no avail. All my MS Office 2000 Programs are gone! Help!???