Be careful about swapping a new drive into the PB150. The HD driver is in ROM, and a third party drive will work only if it's unformatted. See this page for more info:
http://docs.info.apple.com/article.html?artnum=19644
And get a utility disk image with the necessary drive formatter here:
http://charm.cs.uiuc.edu/users/olawlor/mac/mac_PB_150.html
Matt