I doubt you'll get ultimate answers on that. Depends too much on what kind of work you do and the pricing and avialability of components varies from region to region. If you can, get the most powerful core7i processor you can afford (or one of AMD's new Bulldozer processors) and lots of RAM. The graphics card is probably the least of your worries. AE doesn't use it much and if your scenes are not that extreme, even 3D programs will be perfectly happy with 200 $ Radeon/ GeForce cards.
Mylenium what would your rate my set-up: Dell Studio XPS 8100 i7 870 @ 2.93 GHz CPU 8GB RAM ATI Radeon 5770 Discrete GPU
if a add another 8GB of RAM to make it 16GB do you think this PC will be by my side for another couple of years?
Sorry Mylenium.. I want to do better Motion graphics (involve 3d stuffs).