If you have Delphi and your client don't like it, simply not say that!

Our "marketing way" is simply say "We develop using Visual Studio" and not mention Visual FoxPro (here have a real extremme bad reputation because the database corruption) and when the guy see that the software WORKS, then he know that is build mainly in VFP (when he need change a report and thing like thats)... Get the idea?

So market the program with ".NET" and let the software & you to prove that Delphi is great...