I've worked with Macs since 1990 & PCs since 1985. I did support for both platforms at a publishing company. Macs are compromised today by having a lack of upgrade paths for video cards, unless you can swing getting a MacPro tower. So the rest of the Macs (non tower) are like other pre-fab comsumer electronics. The older Macs usually had a special upgrade slot (PDS) or NuBus slots, PCI/AGP slots, etc until Steve Jobs returned to Apple. Video cards for Macs were also a bit behind the PC based cards in the GPU area as Apple had to get involved in driver development. For most media development what Apple supplies for graphics in iMacs, MacBook Pros is all you would need. For high end graphics work-3ds Max is PC only, Maya works on Macs although getting a certified video card may require MacPro tower.
I have a cheapo PC with a PCIe slot that allows me an upgrade path to very recent video cards, as long as my power supply can supply the juice.
Erika