The Release Candidate 1 (RC1) update to the Hyper-V role provides improvements to security, stability, performance, user experience, forward compatibility of configurations, and the programming model. All users of the Hyper-V role are encouraged to apply this upgrade. After you install this item, you may have to restart your computer. “Once you have installed this item, it cannot be removed.”
That last sentence sounds a little fishy to me. Checking on it.
You’ll likely want the management component updates as well. Another good reason to run Windows Vista instead of Windows XP. Sorry, I could not resist.
Management Console Updates
Windows Vista x64 update - http://www.microsoft.com/downloads/details.aspx?FamilyID=c420d8a3-f0a7-415a-b748-3726d66bf0c3&DisplayLang=en.
Windows Vista x86 update - http://www.microsoft.com/downloads/details.aspx?FamilyID=d0284cee-0e79-4453-895a-11aa8cfe6e6a&DisplayLang=en.
Windows Server 2008 update - http://www.microsoft.com/downloads/details.aspx?FamilyID=2b357cf0-5691-4f06-a153-5fbd9c3ea4d0&DisplayLang=en.