A word of warning:

On 02/01/06, James Devenish <[EMAIL PROTECTED]> wrote:
> ...you can completely obliterate your cached Gracenote data...

The above advice only applies if you are also willing to lose your
manually-entered data. To prevent iTunes from downloading Gracenote
data in the first place, you would still need to press the "stop"
button during automatic download, or not connect to the Internet
automatically. Hopefully someone else's advice to 'trash prefs' will
restore your option to avoid the Gracenote downloads in future.