As you have noted, you will probably need to create an EXE file for XP and one for 7. You could have a virtual machine with XP to use it when compiling applications for XP clients.
–I’m new to VB6, where do I instruct VB to build for XP?———-
Your files created by your VB 6.0 software has its exact document path for it to be opened. You have to change the path of the document from your VB program for you to also run in different version of Operating System.