We use Windows Deployment Services to remote install windows client OS's accross the network.
Also, I think your idea of virtualization is spot on for server hardware. I love the technology. I've never used HyperV.
Our current virtualization environment consists of three physical HP Blade servers (Dual quadcore Zeon, 10GB RAM) clustered using VMWare ESX 3.5 giving a combined pool of 30GB RAM and 24 logical CPUs. The server pool currently hosts 11 virtual servers including 2 additional Domain Controllers, a SharePoint server, an ISA server, a web server, software server, etc. Performance is brilliant. We also use VMotion which allows you to migrate running virtual servers from one physical host to another with no impact on performance of the virtual server or end users. It was also do this automatically if a physical server becomes degraded.
I love it. I seriously believe virtualization is the way forward!
With regards your physical servers, as part of your disaster recovery policy you should have the very best hardware support you can get/afford (i.e. if a disk fails, log it and support will have a new one sent straight away).
Or another option would be to keep a stock of the most common server parts that fail.
Hope this continues to be helpful.
IT Services Manager