There is none. So you want to use Mac OS X. Which version are you planning to use? Snow leopard or Lion version? Most software for Mac OS X requires your mac version to be higher than 10.6. Those are for new apps. Snow leopard is 10.6.5 and Lion is 10.7
So you need to buy the dics. After you install snow leopard 10.6.5 you can use software update to upgrade to snow leopard latest version update 10.6.8. You can go to the app store and download any softwares you want.
If you have any mac problems, feel free to ask me. I am willing to help and good luck;)