can an apple powerbook handle editing in high definition, or will it choke? anyone know?

Current Mac laptops come with iMovie HD, so, technically, yes you can but more info about what HD format you want to use, what camera you'll be using, etc is needed.

There is a forum for Lumiere HD (http://www.dvinfo.net/conf/forumdisplay.php?s=&forumid=77) which is an HD acquisition tool for FCP HD that might give you more answers.

The only HD codec FCP HD uses currently is DVCPro HD and the only camera using it (that I know of) is the $60,000 Panasonic Varicam.