Currently using an SSD and HD combo so I have no optical drive, obviously. My SSD is split into 2 partitions - one has Windows 7 on it, but I need to upgrade it to Win7-64. I've made a GUID USB drive and restored the W7 install image onto it but can't get it to boot from this drive no matter what I do! Have tried using rEFIt as well as regular boot device selection on startup, no luck. Anyone else dealt with this?