Thanks for the great explanation of the differeneces. I'm no Quartz expert either as the work I've needed to do on the Mac has either been UNIX based and didn't use the UI at all, or used Cocoa which handles those particulars for you.
There is some relationship between Quartz and display PDF, although I never really quite understood what it was, but it may help in providing the vector based capabilities of Avalon in MacOS X in some later version. Microsoft is being pretty far sighted by putting this into their own implemetation, but I also wonder how long it will be before this makes it into a release.
Anyhow, the vector based transforms will probably be very important soon. From what I understand, light emitting plastic technologies that are just coming to market now will be capable of producing cheap displays with high DPIs. The WYSIWYG nature of both the mac and windows will require it to support screen DPIs close to what we are used to in printers, instead of just assuming everything is 72dpi regardless of the actual pixel density, as most software does now. Its pretty exciting to consider the possibilities available with this combition of hardware and software.