Just a more comprehensive solution for all those of you who still don't fully understand what's going on with the ipsw becoming a zip and unpacking; you have the "Open 'safe' files after downloading" box checked in your safari preferences. You need to disable this as it automatically converts your ipsw file into a zip, unpacks it and then deletes the original file. Check your trash to see if there is a file called iPhone1,2_2.0_5A347_Restore.zip or iPhone1,2_2.0_5A347_Restore.ipsw in your trash. If there is the zip, you need to move it out of the trash then change the extension to ipsw and tell itunes to open it then. If it is already ipsw then just move it out of the trash and tell itunes to use that. If there is no file there, right click on the folder that safari created, tell it to compress to zip, and then when that is done rename the extension to ipsw etc. (Sometimes leopard users will find the files downloaded and expanded by safari to be trashed, while I think Tiger just keeps them at the download location, dunno though as it's been awhile since I last used tiger)