Ben Armstrong's blog post details links to downloads and pre-requisites for the Hyper-V Management tools for Vista SP1. See Hyper-V library content

Microsoft Remote Server Administration Tools (RSAT) enable IT administrators to remotely manage roles and features in Windows Server 2008 from a computer running Windows Vista with SP1. You can also download Microsoft Remote Server Administration Tools for Windows Vista for x64-based Systems.

Windows Vista Service Pack 1 (SP1) is an update to Windows Vista in response to customer feedback. It contains previously released updates and changes focused on addressing specific reliability, performance, and compatibility issues; supporting new types of hardware; and adding support for several emerging standards, making it easier for IT administrators to deploy and manage Windows Vista. Windows Vista Service Pack 1 Five Language Standalone version can be installed on systems with any of the following language versions: English (US), French, German, Japanese, or Spanish (Traditional).