At this point, go with Intel for the processor. We need diversity, and AMD provides that, but at this point their processors are behind Intel in the "bang for Euro" stakes. I like the four core, no hyperthreading i5s, but that's me.
Get a 64 bit OS, it may be that 4GB is technically enough at this point, but sometime in the not too distant future it won't be.
For graphics cards, work out the naming systems then go with what you fancy, Tom's Hardware thought 6GB on a graphics card wasn't getting fully used:
http://www.tomshardware.com/reviews/...-6gb,3264.html