i will not use this primarily for spyware/trojan detection.
i am going to use the antivirus in windows server 2003 for file server virus detection.
this server is a webserver.
im not even sure if those works on the background scanning for viruses.
chuck56 mentioned some very good fileserver antivirus (and very expensive too).
the antivirus i use highly depends upong the os i am using. i dont see many antivirus that works with windows server 2003 (for now).