You can get them from here: http://download.cnet.com/The-Visual-Studio-2005-extensions-for-NET-Framework-3-0-WCF-WPF-November-2006-CTP/3000-10250_4-10727672.html.
This was the last version Microsoft released before telling everyone to go with VS2008. If you can't do VS2008, this is an ok solution. We used it for a year and a half and have production UIs running based on it. The problems are that the designer is basically non-existent (so be ready to code XAML by hand), it can be a bit slow, and there's some bugs.
Re: 3.5, VS 2005 is incapable of handling 3.5 projects, linq, etc. If you really want, you can work outside of VS and just use msbuild 3.5. An interesting fact: .Net 3.5 replaces, among some libraries, the PresentationFramework assembly. The new version of this assembly includes additional methods and method signatures that are not included in .Net 3.0. This means that these new 3.5 methods will be accessible in VS2005.