S. Somasegar has a post on his blog about the delay in the release of VS 2005 SP1 (it was due in Q3 2006 but it seems we cannot expect it before late Q4 2006/Q1 2007.
He also mentions that Visual Studio 2002/2003 will not be supported on Windows Vista as a development platform, however you can still use Windows XP to develop applications that target CLR 1.x and run it on Windows Vista.