Downloaded the SQL Server 2005 June CTP from MSDN over the weekend to install with VS.NET 2005 Beta 2 on a clean XP Pro o/s. As it the June CTP downloaded I installed VS.NET 2005 beta 2 which I already had ready.
My mistake. You must install SQL Server 2005 June CTP first as the setup will refuse to run if it detects VS.NET 2005 Beta 2. A lot of uninstalling (about 10 items in add/remove programs) and it's working fine. Now I can find out if VS.NET 2005 and subversion (an open source, source code control system) get along happily, unlike VS.NET 2003.