I have an Zenith 8088 with duel 5.25" floppies and a 6" monochrome screen.
Yah, it's portable, even though it weighs about 40 pounds. 😉
Seriously, I have had three notebooks - all of which have been lugged extensibly for college/work. Your case and what you put in it is going to make all the difference in the world. PB Wallstreet wasn't bad to haul around as long as I didn't have to bring all of my drive bays, AC adapter, and spare battery along. I currently have a 12" PB Rev. A. Even then, tacking on the external Zip, the AC adapter, trackball, external HD, USB Hub (anyone else notice the ports are way too close together, especally if you use an iPod?), and sometimes even a printer or scanner can really make it a pain to move around. So the portability really depends on bringing along no more then you need. In most cases, I just have my PB and a spare battery or an AC adapter. That's it.