Simon,
>...I have recently been doing some ASP.Net and got on really well with it. The annoying thing though is that the client has still not launched their business properly so there would have been time for the .Net version.
Design your VFP app with a good business object approach and you can perhaps in a later phase compile them into MTDLLs that can be called from ASP.NET to return XML compatible with (and readable into) .NET DataSets. Get your client some web functionality when they need it that way.