ozone said:bump... any advice based on my situation? Thanks.
My $.02: If you like the portability of your lightweight computer, I'd think pretty hard about jumping to the 17". You can always add a monitor later if the 12" or 15" don't offer enough video real estate.
For me, I was in the same boat just over a year ago. Based on endlessly reading these forums I'd decided I wanted the 17". Thankfully, I stopped by an Apple store and used it for a while, because I realized the 15" was more than big enough for me.
It's been said many times in this post already, but it seems worth repeating: Go try out all the configurations you're interested in. Other folks opinions are just that: opinions. They can be useful, but they don't compare to personal experience.
Sounds like you had a 17" PB for a short while before the problems hit? If that's true and you have access to your coworker's 15" PB, you're probably in the best position to decide between the two.
As for ibook + imac vs. PB, that sounds like a whole separate issue...