Fernando Bunn has some very helpful advice if it happens to be 2005 where you are:
The future is here! You have just spent $129 for the newest release of Mac OS X: Tiger. You’re amazed by the brand new Spotlight and Safari RSS, you like your new OS so much you want to develop apps for it. You read on Apple’s website about this app “Xcode” that just received the version 2.0 update. That’s it! Time to code!