I have had a Fujitsu S6110 (1.2GHz Pentium III-M, 768M RAM, 60G HD, etc.) for a few years now. When it was newer I could get 4 hours out of the battery by turning off things like sound, NIC and wifi, dimming the disply, and not using the optical drive. This was always enough to get through a 2 hour CS class + 1 hour lab with various note taking and a few compiles during lab. With UAE I'd get less than half of that.