I am using 10.2 on an iBook 700mhz right now and it does take advantage of quartz extreme. I have 384mb of ram in this thing and it flies, though i am having a problem with how it handles the ram but i'm sure that will be fixed in 10.2.1....it just seems to pageout a lot more often than in os 10.1.5 =/ But overall it's very quick and works very well.