I'm running Win7 64bit w/ 4 gigs of ram and have been working recently with some large assemblies.  My ram usage ends up around 3.2gig or more used up depending on what other applications I have running at the time.  SW starts to slow way down, doing a section view of the assembly takes several minutes, etc...

My computer is a Dell Precision M6300 with all the bells and whistles, Core 2 Extreme 2.8ghz, nvidia quadro fx 3600m...etc..etc...

And no, I don't suffer real bad crashing problems.  Just runs slow in those cases.  The rest of the time it is real quick and responsive.

Thanks,

BM