Why can't I find a download for Interface Builder?

I want to learn to write applications using AppleScript Studio, but can’t find the door. Please point the way.

Download and install XCode. AppleScriptStudio is part of it (integrated into it) and Interface Builder is also part of XCode.

Thank you, hvdwolf.

I downloaded Xcode 2.5 Developer Tools but discovered I have too little space left to install it. I have a ton of files in iTunes. If I Command-Drag the iTunes “Music” icon to an outboard disk, or change its location via Preferences:Advanced, will that free up some space - without causing problems with iTunes?