Being realistic, if you actually open up those six programs at the same time on 768mb of memory, and actually start *doing* things in them while frequently switching between all the given pairs of two within the six programs, you are going to get memory caching. But unless you're doing this specifically to test your computer, in real life, the memory caching should be fairly minimal. What are you really doing that needs six apps at once to do it, and especially that particular set of six apps?
FWIW, when I want to use 1-2 Office 04 apps in 640MB of memory, I usually don't shut down what I already have running (which is usually Safari, Mail, Address Book, iTunes, iCal, and Terminal).