You can manage your Hyper-V server and the VMs running on it from a Vista SP1 machine. To manage multiple machines, use System Center Virtual Machine Manager (SCVMM).
Download the Windows Vista x64 Edition (KB949587) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=C420D8A3-F0A7-415A-B748-3726D66BF0C3)
After you have downloaded the package, you will need to modify the start menu to find them (Administrative Tools>Hyper-V Manager).
To start the Hyper-v Manager click Start>Administrative Tools> Hyper-V Manager
For more information about SCVMM see the System Center Virtual Machine Manager TechCenter.