Macs:
Crash are less reliable cost alot of money and the Graphic Engine is working better for audio than on windows. I remeber back to the G5 with its annoying PSU and buggy Logic 7 with its sudden Channel Death issue. Where we are at failing channels, do AVID finally fixed the BUS Bug (which is a feature of PT HD for ages now) ? Or the not properly working AIR Hybrid on mac ? And what about AIR Structure crashes on mac?
Ahh and one left, Digidesigns Aceess Virus TDM failing impementation. I say only a lpf is not a bitcruncher.

Theses days you can even use Mac software on a custom built PC.
Just one way : ->
http://de.art-studios.net/
PC:
Why do you need to turn off AERO to get a DAW running smooth ?
Cubase GUI is very slow under PC.
Windows 7 is unbelievable stable.
Is there a aluminium PC Notebook out there ? Yes ?
Just my experiences...