@philidor: I have heard the opposite about RAM - this is why I'm looking to double from 4 GB to 8 GB. It costs about 200$ for that. But to upgrade to the top-of-the-line CPU costs an extra 350$ which I don't consider to be cost-effective. (I never think you should pay up for top-of-the-line CPU).
The reason for the video card requirement, in my opinion, is so that the main CPU doesn't have to do the video computations (save CPU for Rybka!), and so that the video card RAM can be used instead of the main RAM.
Hi PerfectGent,
That's good advice on the RAM - here is what I'm thinking now. I need to get a 64-bit windows 7 OS, because the 32 bit has a RAM limitation of 4 GB. It seems that I don't care much at all about disk space (so I can live with something "small" like 320 GB). But for RAM I'm looking to upgrade to 8 GB.
My current choices:
Rybka 4 option: 64 bit windows 7, 8 GB RAM, separate video card, separate sound card optional, Intel i5 (dual), ChessBase 10 w Mega, Opening Encyclopedia, Rybka 4.
Deep Rybka 4 option: Same as above; upgrade to Intel i7 (quad), upgrade to Deep Rybka 4.