Powerbook Advice Wanted, New AlBook versus a Pismo 500 Options

[JasonM]

Due to a serious illness in my immediate family, I will probably have to be on the road a lot over the next year. I'm currently using a MDD Dual 867 tower at home, but will need to get a mobile setup so I can continue to work on the road. Here are a two of the options I'd like advice on (especially from anyone actively using a Pismo 500):

1. A Pismo 500, with or without a G4 upgrade. This may be my most economically feasible option at this time (and would allow me to keep my desktop)... if the performance is suitable. To simplify discussion, just assume that I would install the maximum amount of RAM.
2. A new AlBook (probably a 15 or 17"). I know this would probably meet most of my needs, but it'd be nice to get the job done cheaper.

Here's what I'll need it for: (with OSX 10.3 as OS)

1. Finale 2004: I use this both for realtime midi input and the human playback feature for recording rough copies of my work.
2. Max/MSP 4.5: my patches currently create a fairly light CPU load, but they may get more complex in the future.
3. Either Protools or Logic. I haven't invested in either of these yet, but I probably will soon.
4. I might also need to have it drive both audio and video for computer music presentations. This would probably include Max/MSP/Jitter running simultaneously with ProTools.

Thanks in advance for your feedback.