Where are iPad firmware files stored on my computer?

iTunes downloads iOS firmware files and stores them to a default directory on your computer automatically. These Apple firmware files have an .ipsw extension and are located in the following folders:

On Mac computers:
~/Library/iTunes/iPad Software Updates (where ~ is your home directory /Users/<Username>)

On Windows XP:
Documents and Settings\<Username>\Application Data\Apple Computer\iTunes\iPad Software Updates

On Windows Vista and Windows 7:
Users\<Username>\AppData\Roaming\Apple Computer\iTunes\iPad Software Updates