No, you can't. Every version of VS matches particular version of .NET framework. VS 2005 works with 2.0 only. VWD has no ability to switch target frameworks so you won't be able to say 'make this site 1.1'.
In reality, it all depends on what you are planning to do. You can create a web page that only contains controls that are available in both 1.1 and 2.0. In this case page will work in both 1.1 and 2.0 Web sites.
Technically speaking, you do can open 1.1 page in VWD and since 2.0 is backward compatible, you will get intellisense and full designer support. However, remember that VWD itself is running on 2.0, so all intellisense and toolbox elements will be matching 2.0 and you can accidentally user feature that is only available in 2.0 and won't find the mistake until you run the page on 1.1 server.
The scenario is not officially supported, so if you want to use VWD to edit 1.1 pages, you will be on your own (not much different from Matrix though :-))
I personally used VWD Beta 1 to design and code my personal ASP.NET 1.1 site. However, it is just a simple personal site. See http://blogs.msdn.com/mikhailarkhipov/archive/2004/07/27/199312.aspx
Thanks
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