One other thing I would say is that RAM is cheap as chips....when buying a new computer (Mac or PC) you should always max out the RAM to the most that's affordable to you.
Although having said that, I see the new iMacs seem to come with 8GB, which is probably adequate for most average users.... however if you're thinking about implementing my virtualisation note above and therefore installing a copy of VMware with Windows, getting more RAM won't hurt as it means you can allocate a realistic chunk of RAM to the Windows virtual machine.
But you can always add RAM easily at a later date, so can always be done later if you see your utilisation could do with more RAM.
Last edited by mixture; 24th Nov 2012 at 15:20.