Good System for High-End HD Video Editing/Animation/Effects?

Hello, I wanted to know if anyone could recommend some general specs of a system that could comfortably handle doing video work (both import and export as) in HD1080P(1,920 x 1,080). And I need it to be able to also manipulate 3D objects (mostly in After Effects after I bring it in as PSD). I use mostly After Effects. I'm willing to also render out videos in pieces and put them togther in Premere or Final Cut... I'm also open to either MAC or PC.

I have a Intel duo core with 3GB RAM, and it's struggling very much. I was wondering what processor, ram, graphics card, etc I should be working with.

Thanks!