It's not hard. Apple computers are still using commodity hardware - that is, you can buy very similar parts off the shelf to build your own system. The closer you get, the easier it is, but there are forums revolving around tweaks and updates to make just about anything work. Even AMD CPUs, which Apple has never used.
It _does_ take some tinkering, though, and if you aren't comfortable with that (or if your time is valuable enough), you should invest in the real deal. :)
It _does_ take some tinkering, though, and if you aren't comfortable with that (or if your time is valuable enough), you should invest in the real deal. :)