anyhow..i'm in the same boat. I just went from a 12" pb to a 2.2 mbp but after using it for a project i was 2:1 pageins to pageouts. Sure beats my 1:1 pagein/pageout with my pb but still. I'd buy more ram if I saw a good deal i think.
PC2- 5300 and 5400 are all the same modules and run with the same speed but different manufacturers like to label their product bit differently. 667 x 8 = 5336; so some round up to 5400, just to make their products seem like they're a bit more than they are.