Just to pass along info; You must have OS 10.3 in order to Software Update to FCP HD 4.5, plus the newest version of Compressor or Cinema Tools. I tried downloading it unsuccessfully for 3 days on a 56k modem. No one at Apple support could figure out what the problem was - but we figured out via several other people that software update will still try to download but never be successful to update any of this software. Allex