I have a pair of Mac Pro 1.1 that I just upgraded to quad-core X5355 processors, and I have a couple SSDs with 3.5" mounting brackets coming today. Both machines currently have a 500gig/7200rpm drive in bay 1 with Snow Leopard, apps, fonts, utilities. My plan is this: Put the SSD in bay 1, and move the other drives down a bay. Then, while starting up from the Snow Leopard drive, do a clean install of Lion on the SSD, and identify the current Snow Leopard installation as the source of the upgrade, so all the mail account info, printers, sharing settings, etc. transfer over. Then, just designate the SSD as the startup drive, but leave the Snow Leopard install alone in case I need it for something later. Any reason that won't work or is a bad idea? Basically, these are workhorse machines that can't afford to have any downtime, and I want to be able to start up with things just like they are now, in case Lion gives me any problems or some bit of crucial software isn't compatible.