I have a 1800+ and a 2200+mobile. The 1800+ runs good, BUT your right it eats the batteries fast. I think the best batter life I have ever gotten is about 1.5hours. Also something you different have listed is heat. The 1800+ runs very hot, sometimes to the point of shutting down the pc.
The 2200+m runs great. I have never had a problem with it. Heat is never an issue, and batter life is about 3-3.5 hours.
I haven't used a Pentium mobile so I can't help you there. I would stay away from the Cele, Pentium, and the XP. Get either the Pentium mobile or XP mobile and I thing you will be happy. Also get the fasted harddrive and RAM you can afford, those are usually the bottle necks for laptops.
Soltek SL 75FRN2-RL
2600+ TI 4200
Corsair 2x256 3200
If your PC has bugs - del *.* C:\ will kill them.