I just purchased my 6-core MacPro from Apple's website... ...now for memory purchase 1) Noob question alert: Can I buy 16gb (2 x 8gb sticks)? Or, do the 8gb sticks have to installed in threes for performance? 2) Does it matter (quality wise) if I purchase from Trans Intl vs OWC? 3) Do you recommond Hitachi drives vs Barracuda? Or a different brand altoghether? Thanks.