Option for user to ignore particular package?

Hi, I have updated my Thunderbird in Feisty to Thunderbird2 (using a mozilla-updater called Ubuntuzilla). I did this cos I share the Thunderbird profile with WinXP on a dual boot system and I want Thunderbird in Ubuntu to be of the same verson as the one in XP. However, after I did that, update manager in Ubuntu still popup to ask me to install a Thunderbird security update from 1.5.01.2 to 1.5.01.3. While it seems that I should ignore this update, the update icon stay there and will still "notify" me everytime in start up. Is there a way to tell the program that I don't want to update this package and don't notify me anymore and make the package disappear from the upate list? Thanks.