1.52 did help a lot with optimisation, but the hugest maps probably still need at least 512MB. My gig of RAM handles them pretty well, but it's quite system-dependant; some people with what ought to be better systems than mine are still complaining it's unplayable. It seems the page file's quite important too.
With one or two more people we could get an SG going, that'd be neat. Hopefully I'd be able to help you get beyond the pokey-stick stage too - I tend to manage at least rubbing-the-sticks-together-to-make-fire
