I have been an enthsiatic user of Adobe Acrobat for about a decade, having used all "Professional" versions from Acrobat 3 to 9 except 8. I only upgraded from the excellent 7 to 9 because 7 will not run at all on Windows 7.
I am really sorry to have to say Adobe Acrobat 9 is, in my experience, awful. The features for which I use it every day, scanning paper files and then extracting them for archive purposes, just don't work properly. My old Brother scanner worked a treat under XP but is not recognised by the new Windows 7 network so we bought a new network ready HP multifuncion scanner / printer. No problems with that UNTIL you try to scan into Acrobat 9.
Acrobat shows the device as available but just refuses to use it. So you have to scan using the software which came with the HP. A real pain, but at least it produces a pdf image. I had bought Acrobat to do this but it is useless. You can open the pdf files created by the HP in Acrobat - slow, but it works, just.
When we try to work with the files, basic things things like reorganising the page order and extracting pages to new files, the REAL problems start. Acrobat 9 Professional just keeps crashing for no reason, doesn't extract the pages properly and is annoying in many other ways. We run it on high spec Windows 7 machines with 4GB RAM which are many times more powerful than we used with Acrobat Professional 7 on XP yet the files we can safely create without Professional 9 crashing are about 10% of the size we used to use (i.e. 20 pages compared to 200).
If you can avoid buying this terrible version, get something else until Adobe brings out one that does what it promises.