I have IIS on this desktop now, but don't know how to make VWD use it as its development debugging server. VWD seems to insist on using its own server (Cassini maybe? I have no idea).
Also, I don't have the links handy to articles mentioned-- and it was WAY too much work finding them in the first place. However, I did see mention of making a configuration change *somewhere* that allowed legacy asp pages to preview in VWD.
I still think Microsoft's decision to disable this by default is asinine.
Anyway, the point is now moot-- through much persistance and trail-and-error, I managed to get the old asp content working in an asp.net page. I just had to settle for bringing in all of the old html, and using the legacy VBScript code in the body rather than newer VB.Net code (which kept producing errors that made no sense). So, I'm not 100% happy with the means, but I am mostly happy with the results.
Now if I could just figure out why a Microsoft Access report's OnFormat formatting (using VBA) is lost once it's been converted to xml...