I've bought a new rMBP 15 last weekend with a 256 gb SSD. I like it very well so fare although I don't have any experience with a mac. I also have a windows 7 machine so my idea is to add an external storage device which I can use with both machines. I also have a NAS but that's a slow machine so I consider a device with USD and thunderbolt support. Is that a real idea? If yes which device would you advise me to look at? if not, what could be a better solution with an acceptable price?