It's partially true.
I mean for Windows XP 32, it's completely true. Maybe worse than that, even.
But AE is a 32-bit app that runs nicely on 64-bit systems.
In any case, it's not that you can't take advantage of more than 4 GB. It's that you can't address more than 4 GB at the same time, for a single application.
AE drives around this limitation to an extent, by launching a separate rendering application for each physical core in your computer, when you enable the "Render Multiple Frames Simultaneously" feature. So, in this case, it would be "up to 4 GB of RAM per core/rendering instance". A quad core machine could happily use up to 16 GB of RAM, for example.
But ultimately, it's still a limitation. The main app can't use more than 4 GB for RAM previews, for example. And it can become starved when working with very large source files or Compositions (in terms of pixel count, I mean). So, this week announcement about the next version of AE becoming a full-blown, native 64 bit AE is very important in this regard. And the reason why this was announced now is... so that you take this into account when shopping for a new system. Also, fly away from 32-bit operating systems as soon as possible. AE already works much better on 64-bit OSes.
Now, let met stress that there's no such thing as too much RAM. Especially under the light of yesterday's announcement. If you're thinking 6-12 GB, by all means get 12 GB.
Thank you as always Adolfo for all your help and knowledge. I appreciate you taking the time to explain that to me. I'm glad you pointed out that a 64-bit system is the way to go, as I don't want to have to turn around in a year or so and be upgrading again. I would rather bite the bullet now, and get a computer that is still going to do the job down the road. Thanks again.
PS. Would you have a link to the 'announcement' that you refered to?
Wow, great links! Looks like I will be doing some more reading for a while . Thanks again Adolfo.