I'm hoping I can get some advice on what would be the best configuration in terms of speed and price on building an external hard drive. I currently have a bulky WD MyBook 500Gb external HD but it's a pain in the rear to have to put it in my backpack & carry it home on the weekends(occasionally carry it around campus too). It takes up a lot of space, is heavy and I just don't want to deal with that anymore. I basically need it to backup my music, pictures and college work if that makes a difference. So I was looking on sites like newegg and tigerdirect to buy separate hard drive and an enclosure for it. I have a MacBook Pro Unibody(mid 2009) so I wanted to utilize the Firewire 800 & Usb 2.0 features but I haven't had much luck finding drives and enclosures that fit my requirements. Also, is there a significant difference between SATA 3.0 and 6.0? Which one do I need? I would prefer a small physical disk size, 2.5 but are they better than the 3.5 ones? Any pointers would be appreciated, and links would be very helpful too. I'm looking for around a $120-150 budget, but if I can get some for less that would be awesome too.