Hi, I just upgraded my imac to 4gb and now my imac is being disturbed by my itunes files music, video, photos, documents etc i was thinking a good hard drive would fix this and allow me to share items with my pc that im gonna throw out soon ( its EXTREMELY slow) something under $200.00 usd , and something for a desktop could you post some direct links to the external hard drives thanks, and whats the difference between 1tb and 500gb? Which would be faster usb 2.0 or firewire?