If you migrate a VM with Vista or 2008 from Virtual Server, you don’t get full mouse support even when you install Integration Services. By full mouse support, I mean to be able to use mouse from a RDP session connected to the Hyper-V host. You’ll get “Mouse not captured in Remote Desktop Session”.
The solution that I found is adding more than 1 CPU to the virtual machine, and activate detect HAL option. More details in my previous post: https://folgaizer.wordpress.com/2008/07/17/migrating-windows-server-2008-guests-from-virtual-server-to-hyper-v/