When I brought up my most recent Windows development machine (on Vista Ultimate), I installed Visual Studio 2008 Professional with SP1 embedded. Later, I went to install SQL Server 2008 including the "Management Tools" option so that I could have SQL Profiler and the other tools. That's when the problems started. The installation was blocked failing this rule:
Rule "Previous releases of Microsoft Visual Studio 2008" failed
Imagine my surprise when I found this article indicating that the problem was that I didn't have VS 2008 SP1 installed. I'm sure that I was running SP1, because I was seeing SP1 bugs manifested (requiring hotfixes). These bugs were only present in SP1 as of the time of this writing. It seems that a required registry key or something didn't get set when I installed Visual Studio. I really didn't want to get into hacking on the registry.
I downloaded the Visual Studio 2008 SP1 installer and ran it. This took quite a while, and I'm now up much later than I planned. However, I can report that this got me past the installation block. I'm not sure if I'll have to reinstall those hotfixes or not...