Mike,
It looks like I scanned over your email a little too quickly and missed a
VERY important point. You mention that your form will be "bundled with Acrobat 7.0 Professional". This is VERY important.
In fact, you will need to license nothing else from Adobe. You DO NOT need Reader Extensions because you are deploying Acrobat Professional on the work stations that will be filling in your forms. You do not need to "turn on" hidden functionality of the Free Reader if you are using Acrobat Pro. You already have all the functionality you need.
Second, when you fill in a Barcoded Form with Acrobat Professional the PDF417 Barcode that is rendered in your form will be a 100% standard PDF417 Barcode. But do not turn on compression. When filled in - in Acrobat - the Barcode is rendered so that it can be read by ANY Decoder that can read PDF417. However, if you enable compression you will need to use the Adobe Decoder. If you start decoding and see you are getting lower than a 99.9% decode rate, take a look at buying the Adobe Decoder. Not the whole "Barcoded Forms" license, just the Decoder.
Again,
if you are using Acrobat to fill in these forms, you have nothing else to buy. If you want to deploy these forms with the Free Reader then you will need to license Adobe LiveCycle Barcoded Forms and possibly ARES.