This is probably blatantly obvious to most people, but I've seen some confusion on this topic over the last couple of days, so documenting it is probably no great disaster. Some people aren't clear about how you install SQL Server 2005 ("Yukon") Beta 2 and Visual Studio 2005 ("Whidbey") Beta 1 on the same machine.
Although Yukon Beta 2 and Whidbey Beta 1 are designed to work together, Yukon shipped about a month later to allow a little longer for bake-testing. The one thing you have to watch out for is that Yukon Beta 2 installs a slightly later version of the .NET Framework (2.0.40607.42, which we'll call Beta 1+ for simplicity) than Whidbey (2.0.40607.16). Visual Studio 2005 can run on either version of the Framework, but SQL Server 2005 depends on the later version as a result of some late bugfixes. So how do you install them together?
If you're starting with a clean machine, the simple answer is to install SQL Server before Visual Studio - that way, the Beta 1+ version of the Framework is already on the machine by the time VS setup runs.
But a lot of people installed VS 2005 as soon as it came out and are perhaps confused by the error message they get from SQL Server when they try to install it. If you find yourself in that situation, uninstall the Beta 1 release of the Framework and then install SQL Server 2005, which will install both Beta 1+ of the Framework and the database engine itself. There's no need to uninstall the whole of VS 2005, just the .NET Framework itself. Clear as mud?
Once again, apologies if this is blatantly obvious, but perhaps it will save someone ten minutes' frustration.