What will your users have? Acrobat or Reader?
If Reader, you have some limitations (unless you do spend some money). These limitations concern XFA forms, which will need Extended Rights to be saveable in Reader.
PDF forms (using Acroforms technology) do not need Extended Rights if Reader XI is used; older versions do need Extended Rights.
That said, and also mentioning that I am a little bit biased, IMHO, it would be more future-proof to create PDF forms, mainly following the classical way to create (do the base form in a layout program, then add fields and logic with Acrobat (in this case, you either have Acrobat 7, or then you better work with Acrobat XI).
In any case, spend a good time with analyzing and planning the forms; for instance come up with a good field naming scheme, which will have an effect on the time you spend when it comes to add logic.
Hope this can help.
Max Wyss.