Do any other hosts offer Windows VPSs using Xen-HVM? Where do you purchase licenses to resell the VPSs with windows on them? Also, Do you provide Windows templates or use Windows ISOs?

the windows license is different from hosting environment as far as I can tell you.

Windows Licences for service providers are dealt with under the SPLA and you get through an SPLA partner ...

Basically you can get such licenses from your DC or provider. It's not easy to resell such licenses.

You should offer Windows VPS solutions based on Hyper-V platform. Hyper-V is a more cost effective and better option, as you won't have to pay additional charges for Windows OS, because Hyper-V is a part of the Windows Server 2008 Data Center Edition.

Best way to get licenses is through a SPLA.

http://www.microsoft.com/licensing/l...a-program.aspx