Install both frameworks. In IIS 6, set each to run in its own application pool and set each application to run the correct app pool for the framework in use. See www.iis.net for help with IIS, same login as here. VWD 2005 and 2008 will only provide intellisense and other options for 2.0 framework and up. That's why the suggestion for VS2003 for editing 1.x framework apps.
Jeff
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