You must already have a copy of a Windows Operating System. Boot Camp Assistant basically creates a partition just for Windows without erasing your existing Mac OS X volume. After running Boot Camp and installing Windows, you can switch between Windows and Mac OS X by holding the Option key at start up. Or, use the Startup Disk control panel in Windows (installed with Boot Camp drivers from the Mac OS X installation disc) or Mac OS X Startup Disk preferences to set the default operating system to use each time the computer starts up. Programs such as 'Parallels Desktop 6 for Mac' and 'VMware Fusion 3' are terrific add-ons for Boot Camp that allow you to open Windows-based applications without switching between your Windows and Mac OS X partitions. Hope you found this helpful!
Matt Thompson
XcodeCrazy
June 30, 2011