I am new to developing for Office Forms Server / MOSS 2007. I have to choose between designing my web-based forms and writing code for them in Visual Studio Tools for Applications (aka VSTA) or Visual Studio Tools for Office (aka VSTO). VSTA is included free as part of the license for InfoPath 2007; VSTO, also free, requires Visual Studio 2005 / 2008. I have licenses for both of the products and cannot easily decide what the pros and cons of each IDE might be.

+2  A: 

This explains it better than I can:

Given the fact that the license for VSTA comes with InfoPath, I'd probably run with that.

Bennor McCarthy

To add to Bennor's answer I would avoid writing code "behind" InfoPath forms entirely. This is a desperate attempt to make 'dumb XML' as much as possible instead of "smart" XML that is entangled with code. Failing this, my next choice is VSTA because historically these solutions (at least the ones I have written) have a lower security risk and can run on more diverse Office environments.

The last resort is to use VSTO. This is my bias... most of my VSTO investments are in Microsoft Word.