I've read a lot about hacks to install leopard on pcs, but no one ever says what happens if you just stick the leopard disk in and boot from it normally. What goes wrong when you do that?

It depend which hack installation you want to install from. So of them make installtion too easy that it will install as you are installing XP or Vista but some are a bit more difficult. So you must know which one to install.

There are lots of hacks for Leopard installers, some are borderline impossible, while others are DECENT.

A well known one is JaS OS 10.5.1 but it still has lots of hardware compatablity bugs and can be a little tough to install.

EFI-X makes a USB dongle thing that can supposedly help install OS X on a generic PC with the normal retail disc. It even handles the drivers. Do a little research on these two things if you're really into it.

...Otherwise, it's kinda not worth it.

I wasn't talking about installing from a hacked version of leopard. I was wondering what would happen if you tried to install leopard from the disk that you would buy from apple. What would happen that would stop it from workng?

It would probably not detect an EFI capable motherboard & would quit the install. Now I think this thread is borderline as it is, may I suggest the linking to "delicate" software be kept to a minimum.

I won't work definitely... As the EFI motherboard won't be detected that is important for the Leopard OS X installation as it is the only support allow by apple OS.