I went back a few pages in this thread and didn't see anything. Don't crucify me for asking, but is Adobe needed at all on a Mac?
Maybe you should define what you mean with "Adobe".
I'm pretty sure that Photoshop, Dreamweaver and the army of other Adobe creative/design applications are definitely needed on the Mac, especially since there are no real alternatives to them on - any - platform.
Or are you just talking about the browser plugins? Of course you need Flash on the Mac: HTML5 still is nowhere to be seen, and it's not even an accepted standard yet. Everybody's TALKING about HTML5, but at this point in time, HTML5 is still a Science-Fiction technology.
Do you need the Adobe Reader? It depends on the kind of PDF files that you need to open, view, print and maybe even edit. Apple's Preview application handles most of the basic stuff at an acceptable level, but there's plenty of stuff where you just need Adobe Reader and its advanced PDF support.
At the end of the day, you'll need to install a bunch of additional software on BOTH Windows and Mac OS X to get a fully functional system that satisfies one's needs. Windows has some tools on board that OS X lacks and OS X in turn lacks some features that Windows has out of the box. Neither platform is ready for "prime time" use out of the box. (The same is true for any flavor of Linux, by the way.)