I don't know much about how RAM, video card and processor speed affect performance for AE and Premiere. I am looking into buying a new Mac (maybe a laptop maybe an iMac). I want to spend under $2,000 so I am not looking into a tower. Is 8GB RAM and a 3.2 GHz enough to let everything run smoothly? What component should be prioritized here?
You need a balanced system -- prioritizing one subsystem at the expense of others will not benefit you. For example, the fastest CPU in the world won't work well if you don't have enough RAM.
I think the easiest (and cheapest) bottleneck to overcome is RAM, and which both Ae and Pr will put to excellent use. I'd look at a minimum of 16 GB of RAM for Pr in general, and for Ae use on a quad-core system.
The graphics card matters a great deal to acceleration of specific operations and effects in Pr. See the tech specs [link] for the list of approved GPUs. (Some people are using non-approved cards with good results, but I'm not sure if that includes the current iMac.)
The new iMac's GPU looks promising, but the machine hasn't been released, tested, or qualified yet.
Ae uses NVIDIA GPUs with CUDA for accelerating the new ray-tracing renderer. CPU-only mode still works with all the same functionality, but much less speed. If you're using the classic 3D renderer (as found in CS5.5 and previous), then this isn't a large factor for you.
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