Hi, I am thinking about retiring the 17" PowerBook and moving over to my girl's Macbook Air. I really like the PowerBook, it is still fast, but the screen has developed about 7 vertical lines and it is heavy and limited to Leopard! I would like to take advantage of iCloud and need Lion... The MacBook Air is the 2010 128GB model, I want to keep my and my girl's accounts and backups separate. So am thinking to use my Time Machine Backup to migrate to a new install of Lion on the Air, but installing the OS on a new fast 64GB USB thumbdrive. (The USB3 drives are pumping out 100MB/s + speeds, but would be looking at the 30-40MB/s range as USB2 is limited to that area). Any ideas on the performance I am likely to get? Is this a good option? Or should I migrate my data to the MacBook air as a new user?