Good method of deploying windows 7 in XenServer

We are currently looking for a good way to push windows 7 to 30 WYSE RDP thin clients. We want the windows 7's to all be the same, and authenticate the users against AD. So we think we need to virtualize Windows Server 2008 R2 to act as AD. Our place normally uses Deep Freeze, but it keeps us on our toes for rolling out updates ect. We think we might use Windows 7's Guest mode to protect the systems form modifications, though I'll gladly take recommendations for that. So here's my questions.

1. What's the best means to deploy 30-200VM's of windows 7, most likely using Volume Licensing. We want this to be as automated as possible, with very little or none individual VM configuring.

2. What can we do for virus protection. We currently use McAffee enterprise, but it's a horrible load on the physical systems. It seems that on a server farm running 200 machines, that it's a waste to use a virus scanning program on each individual machine on the same code over and over.

Thanks for the help!