Can I use a non-Apple keyboard with OS X?
Macs work just fine with non-Apple keyboards. Alt becomes option, and the Windows key becomes the command key. And if you want to rearrange them, you can easily do so in the System Preferences:



However, I prefer to use Apple keyboards with my Mac as they have buttons on the top to control expose, volume, and pause/rewind/fastforward of media playback. Apple keyboards also have the command key better positioned for keyboard shortcuts than the Windows key is on regular keyboards.