"If they want to buy technology (.NET) rather than a solution then you're right- there's really nothing you can do.
".NET, as far as I know, is no magic solution for web apps - you still need to deal with HTML and Javascript. These are common elements that need to be dealt with in any web app.
Claude,
Some of us have been building working 'solutions' in .NET already ;)
As for the 2nd statement, not all 'web apps' need to deal with HTML and JavaScript...
A web application in .NET (and even in VFP 8) can feature a distributed architecture with a 'smart-client' piece in Winforms that communicates with a .NET web service through XML, which can (in turn) work with the application/middle tier (either straight shot or through remoting). All wtihout HTML, JavaScript, etc.
Granted, the end-users must be running the .NET framework, but it's still web-based, and is becoming increasingly popular as an architecture for corporations with many remote users/sales forces, with UI requirements that go beyond a browser's capabilities. It's also profoundly stated in tech papers on MSDN with titles like 'Death of the Browser'.
Kevin