Some days ago, I bought a Lenovo 3000 N200, and I'm quite happy with it. I'm using ArchLinux and Gentoo, and Linux often provides a bit more of information than windows does. So, I think there are some things the battery gives correct information about (the following is full-charged output of /proc/acpi/battery/BAT1/info):
present: yes design capacity: 5100 mAh last full capacity: 5100 mAh battery technology: rechargeable design voltage: 11100 mV design capacity warning: 420 mAh design capacity low: 156 mAh capacity granularity 1: 264 mAh capacity granularity 2: 3780 mAh model number: PA3465U serial number: ##### battery type: Li-Ion OEM info: COMPAL
but the output of /proc/acpi/battery/BAT1/state (as follows)
present: yes capacity state: ok charging state: charged present rate: 0 mA remaining capacity: 5100 mAh present voltage: 11100 mV
always says present rate 0mA (and also always the specified voltage, what in-fact is quite not possible). That explains why some battery-watching-tools can guess a time, but can't do it instantly, just after watching the remainig capacity over some time - they just don't get a current mA-rate.
I also wonder why it's BAT1 and not BAT0, in fact there is no BAT0...
A second problem is (but in this point, I'm not sure yet if it's my own fault), that my cpu is, while idle, only 50% time in C2-state, the remaining 50% it's in C0 (and that with 150 - 200 wakeups / sec). Thats a bit stupid, because it's a waste of energy, and other laptops with dualcore do it without problems.