AFAIK, there is no way of accessing the extra partitions on the flash drives via USB. Secondly, the way dual booting usually works is that you copy your current system to the SD card and then install the new system to the (internal) flash. This can certainly be done with OS2007 and OS2008, but as technut said, you will not be able to use WiFi with the OS2007 installation, which renders it pretty useless IMHO.