Dear Rachel,

Nearly all the posts here do make sense. You should buy a Mac for the additional diversity and experience. There are no cross platform issues I have run across since OSX arrived but the old “Classic” well it was a different world.
Using Linux you will understand the basic principles of OSX already relating to the kernel and the stability and security of the systems. They do what root tells them to do su-
Now my instinct tells me (partly as OSX grew from nExt OS) that OSXI the next leap will in as much support X11 instead of the frakenstein way it does now (but it does work). Pixar run rendering farms on Linux workstations but their Renderman runs on OSX.
Tiger will have some very neat innovations like XGrid (but you will have 1 machine so it won’t help you much) it is also fully 64 bit compliant and if you want to fill up your machine with RAM for modelling or other intensive processes very nice.

Get one, Apple support is good if your hardware fails and the culture of the computer they have is that they should help you.

Just don’t wait too long……..