I am currently administering a windows LAN of approx 50 windows XP Pro machines. Everything on the backend and the systems department is running gentoo linux. I am looking for solutions that will help me manage the Windows XP pro LAN, perferably from a linux platform. Of course, I am aware of network monitoring tools like ethereal, netcat, etc. I am looking more or less for tools that I can get reports on bandwidth usage, patterns, possible virus alerts (?) If I have to throw in a windows client or server for administration I suppose that is always possible, but I would rather not if I didn't have to ;-) . Any suggestions would be greatly appreciated.

There are a lot of programs that you could use. MRTG for bandwith usage, ngrep for patterns, snort for virus alerts and network intrusion.. There isn't all-tools-combined-in-one :P