difference between a Mac and a PC

[Nvidiaguy07]

i was looking at macs the other day and noticed there made with all the same parts as a PC. Why cant you install leopard on a PC computer?

I've heard there are hacked versions of leopard out there for pc. are they any good?

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EDIT: for example if i needed a new CPU for my mac and it was using a intel core 2 duo processor, could i just buy a regular one and put it in my mac? and if thats true then why cant i just upgrade every part (basically build from scratch) and still have a mac?

 

[noriseghir]

Mac don't have conventionnal BIOS but EFI and Mac OS-X is writen to boot and work with this interface. But there's workarounds : example

 

[Lonyo]

Macs use EFI instead of the BIOS that most Windows PC's use. You can install OSX on standard "PC" components, with some fair tweaking, but only on the hardware Apple use, because those are the only ones with Apple support.

 

[Aluvus]

The motherboards are specially "blessed", the processors are just off-the-shelf parts.