The usual MS solution for software development on a PDA is the "Embedded Visual Tools" package which comes with embedded Visual C++ *and* embedded Visual Basic. Symbol usually also provide the APIs you need to interface with their hardware.
Alternatively, you can go down the Java route. Many integrated development environments for Java are free (e.g. Eclipse). Although Java is easier to develop with than Visual C++ / C++, it is *much* harder than VB. Also, Java development on a Symbol handheld will require a small-footprint JVM. Symbol do provide (or atleast used to provide) the NSIcom Creme JVM with some of their handhelds, but a preferred option would be the J9 JVM from IBM designed for small-footprint devices. IBM also provide a 'Device Developer' edition of their Java development environment, but it's not free.