I'm new to SD cards and intrigued by it's possibilities with the new Mac mini. Can I use say a SDHC or even a SDXC card as a Media-Folder for iTunes? I'd rather not 'clutter' the Hard-Drive with music files and this would seem more convenient than using an external HD. Will it work, and considering the read/write speeds, would I have to get the highest 'speed-class' card?