Visual Studio Beta Removal tool. When I had this problem it solved it right up for me. Unfortunately, I think Windows got confused with all the installing/un-installing that was going on. He got his machine to the point where SQL Server wouldn't show up in the add/remove programs list, he couldn't run the un-installer for it because it wasn't present, and he couldn't re-install the same CTP version to uninstall it correctly. And of course he couldn't install VS 2005. It seemed like he was in a real tough spot, we searched around for more information about how to get around this situation. I found a tool, the Windows Installer Clean Up tool, that can be used to removal applications and installer files from failed apps that don't show up in the add/remove programs list. When he ran this tool he was able to see and remove the SQL related components. Following this he was able to install the correct versions of SQL Server 2005 & Visual Studio 2005.
Sayed Ibrahim Hashimi