I recently bought a Macbook Air to go with my iMac, principally to use as repository for large pix files when I'm traveling. Rather than jamming up the Air's HD, I'd like to transfer the pix to an external drive. A flash drive would suit this purpose, right? bUt I'm think an external drive also would give me the ability to load a new program on the Air without having to first load it on the iMac and then transitioning it to the Air. BTW, I'm a recent convert to Apple and I'm still trying to learn the Mac system after many, many years with MS. Suggestions and recommendations would be appreciated.