How similar are the PC and Mac versions of Premiere Pro and After Effects CS 5.5? Can a user of these programs easily switch from one platform to the other? Are there program features that work in one version but not the other? Are there any usage differences? What about the projects; can they be interchanged between the two platform versions?

With the sole exception of levels command in Premiere Pro they are identical.

We've been successfully running parallel PC/Mac setup and exchanging projects back and forth without any problem since CS3.

there are some transitions in PP / PC that aren't in the Mac version - pretty much the goofy ones you'd never use anyway. otherwise pretty much identical.

same requirements for CUDA too - a supported nVidia card

I switched to mac pro back when cs3 came out. On the whole there isnt much difference in premiere itself. Just a few missing effects and transitions.

The surrounding ecosystem is quite different though:
There are more video card options on the pc, including cheaper CUDA options and they come to market faster.
Cineform and other 3rd party support for PPro on the mac has lagged sometimes by over a year.
Onlocation and Audition were missing at first but have now made their way to the mac.

Given Apple's increasing focus on consumer level tech, if I had to make the choice again now I think I would buy a top of the line Workstation class PC from HP or IBM. The mac interface lured me over initially and there is still a lot that it does better and more simply than the MS Windows, but Windows 7 seems to have made a comeback, and Windows 8 looks like it might be better still.

If you are just deciding by what's out there now, then a mac pro is definitely a beautiful piece of hardware. It's so easy to add hard drives and ram to it, and the handles make moving it around easier too. I'd say its best designed workstation out there. Just not sure how long that is going to last.

there are some transitions in PP / PC that aren't in the Mac version - pretty much the goofy ones you'd never use anyway. otherwise pretty much identical.

same requirements for CUDA too - a supported nVidia card

Steve, I journeyed over to your site and read that you have the Quadro 4000 in a Mac Pro. How's that working out for you?

Are you utilizing it in both the Mac and Windows OS (via Bootcamp) environments?

I was reading the reviews / comments on the Apple site regarding this card and, overall, it seemed like it was a buggy card for them. And I think at least one user claimed it worked flawlessly under Windows 7 (Bootcamp'd of course) but not so well under the Mac OS....but there may have been an update to either the OS or the card itself or both to alleviate those alleged problems.

Your thoughts and experiences?

thanks for taking a look. I've had the card in the machine for a day, so too early to say. it works great with adobe apps and thats all I care about. I know on barefeats.com they say its slow next to the 4800 on some games or motion but I'm not doing either so I don't care. I expect it will get sorted out eventually.

what I will say is that apple hasn't been giving nV much love these days, using pretty much all ATI / AMD chips / cards in their machines, but you know they swing back and forth ever couple of years so who knows.

I use virtualbox about twice a year to run XP, boot camp I don't mess with anymore since my need for windoze is just so limited. I also have an old PC here with XP SP3 for web testing stuff so I'm pretty much covered.