I may be burn on the stake for this suggestion.
If your concern is hosting on Linux (vs. Windows), and you are relatively happy with ASP/VB then you may want to look for hosting companies running Chillisoft which allows you to run ASP (ASP 2.0) on Linux. Then pretty much what you have to do is change to ODBC DB calls. This may be a reasonable (or short term) alternative to re-doing your program from scratch in a new language (regarless of how great the new language is-- PHP is very good).
Just an idea, may or may not be what you are looking for