Not a regular user, but I've used
Knoppix to save files to a USB drive on more than one occasion when the OS on the primary hard disk has got corrupted, won't boot and needs reformatting... does this count? I don't know much about Linux and needed help when using the command prompt but I loved the Knoppix GUI. When I reformat my other computer soon I'll look at dual-booting it with WinXP and Linux.