If you are a freak like me and can't wait to install Vista, although you know there will be many compatibility problems so early after a release, you might encounter some problems when you try to install SQL Server 2005 Express Edition on a Vista machine (MSDE will NOT be supported).
There is a website however that can help you with configuring everything to make SQL Server work on your Vista PC. So if you can't wait for Service Pack 2 check out this website.
There is also a little post-SP1 download for Visual Studio 2005 available.
And for the people who want to run Virtual Server 2005 R2 there is this link.