RAM is important (especially for After Effects). 12GB is the amount where people seem to begin to have smooth and trouble-free experiences with things like HD and Dynamic Link.
An Nvidia graphics card is a good idea for Premiere Pro, especially one of the cards that provides CUDA acceleration features.
Two or three fast local hard disks are a good idea.
Fast processors certainly help. But don’t blow your money on processor cores and then have none left for RAM. For After Effects, a four-core computer with 12GB of RAM is a better idea than an eight-core computer with 8GB of RAM.
FWIW, at home I have a quad-core with 24GB of RAM, three hard disks, and a Quadro CX. That should tell you what my recommendations are better than any generalizations would.
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Todd Kopriva, Adobe Systems Incorporated
Technical Support for professional video software
After Effects Help & Support
Premiere Pro Help & Support
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