Hi guys, This is probably a really obvious question but -- can an external hard drive using Firewire 400 plug into a Firewire 800 port? Does the Powerbook 1.67 15" only have a Firewire 800 port? If I buy a used laptop from a private party, just over a year old, I'm screwed getting AppleCare but are there any other reputable companies that offer a warranty? If you have a laptop, you pretty much NEED a warranty, right? Thanks!