Hi Victor
Incidentally, over here I have developed an Accounting system with modules for Inventory, Order Processing, Central Excise Documentation (a very complicated accounting and inventory reporting system for manufacturer for taxation purposes and to which I am proud to say I have been able to provide the latest updates in the minimum possible time as and when the govt. makes procedural changes, which is pretty often). I have also created a separate Payroll application which interfaces with the main application.
You can check out my website at
http://ahmedabad.sancharnet.in/vso_ad1/ or
http://venussoftop.tripod.com in case you are interested to know about the modules that my application has. I am working on a VFP9 + FireBird version of the same and have started with an Export Documentation module, to which I intend to add the above mentioned modules one by one, though frankly this is slow going as getting all the domain knowledge all over again into a new application.