Point one: Use the most similar hardware you can get!
As I wrote in my first post, it is very helpfull and wise to use "apple compatible hardware". Apple doesn't support much of the hardware that is avalible on the market, some of them can be hacked to its full functionality and some of them still wait for a programmer to write the driver for it, and some of them never will be supported because of small popularity. It is much more easer to bring a pice of hardware that is already used by Apple in Mac Pro`s to be compatible with our hackintosh, as there is a original driver already and in most cases we need only to change few things to get it work with OSX86. Example: Nvidia GeForce 7300GT or the new Radeon HD2600. This graphics cards are used in the Mac Pros and it's fairly easy to install them on OSX86.
The list of OSX86 compatible graphics cards:
