I'm preparing to upgrade from Tiger to Leopard, and have an install of Parallels 3.0 Build 5584 currently running fine on Tiger OS. I'm monitoring Driver49's post and plan to follow Stacey's recommended sequence of uninstall parallels-upgradeOS-reinstall parallels. I'm also following Joe Kissel's great ebook "Take Control of Upgrading to Leopard" which contains very clear instructions for preparing your machine for the upgrade. I will have a complete backup clone of the Tiger drive before making the plunge. So far, two questions: 1. Parallels web page http://www.parallels.com/en/support/leopard/ states "We highly recommend that Parallels Desktop customers only run Parallels Desktop 3.0 Build 5582 on their new Leopard operating systems" Is this correct, or will a re-install of Build 5584 work as well? 2. Of the three OS upgrade options (Upgrade, Archive/Install & Erase/Install) available for the Leopard upgrade, is there a preferred path from the Parallels perspective. Seems like a mute question, given the "uninstall route", but never hurts to ask. p.s. Autocad-version 8 on Windows XP Pro on Parallels 3.0 on a MacPro beats Windows on a PC hands down. No fuss. So far every Parallels upgrade has been smooth and the results are just great. I cringe every time I fire up the old PC.