That's true to an extent, it's more like this:
CPU - Rendering
GPU - Viewport rendering
RAM - Stops maya from crashing.
Macs are fine for what we're doing at uni, in theory. Near all of autodesk's products are mac native, as is the Adobe suite. The issue is the cost as was said earlier, and also it's usespan. You can expect to pay upwards of $1000 spec wise compared to a PC, and you won't be able to upgrade.
If you get a PC, you won't really be able to go wrong with the processor. You'll get what you pay for, look to be spending around $250-$350. The more cores the merrier. AMD don't have a hyperthreading solution, so you'll probably want to go Intel.
For a GPU, your best bet is nVidia. Mostly because maya is notoriously sluggish with ATI cards. nVidia has CUDA technology as well, which is pretty cool, but it's hardly supported in current apps. You don't need to spend an outlandish amount here, it's practically only used for viewport rendering. Unless you have a production specific card like a Quadro which cost a s***-ton, you won't notice too much difference. GPU rendering or at least visualisation is the way of the future though, checkout
Iray. that's hidden in maya, right now.
Throw in as much RAM as possible. It's cheap, and once you start working with massive textures and massive scene files, you will use it all. I think Rowan & Bridgets project was using 2k texture maps just for the old mans face? taking into account the scene usage, windows and whatever else is open, that's probably 4gb there. If you're CPU supports tri-channel memory, go with 6 or 12gb. If it doesn't, (I
think only the 1366 socket does) go with 8gb.
And x64 windows