Macs are really easy to use, and are very reliable--not hard to learn at all, and very forgiving--The limitations are that not every consumer device is mac compatible(though if you are persistant, you can often find workarounds), there are fewer games available, and there is less freeware--mac is the standard for music and recording and for graphic arts, and it does that stuff better than PC--it is also really easy to create networks of the macs in your home or office.

As to mutlichannel sound recording PCI cards, you *can* get them for mac, but probably won't need them, because most everything want can be connected by way of USB or Firewire--