Disappointing BigAl battery life

[Selwyn Ward]

I've been a little disappointed with the battery life I'm getting with my
new 17" PB.  I dutifully followed the advice for conditioning the battery,
but even with Energy Saver set in automatic to max battery saver when
running on battery, I'm only getting about 1'50" from a full charge.  I
wasn't expecting the usually quoted but unachievable 4-5 hours, but I'm
disappointed not to be pushing 3 hours when only running Word, Entourage &
Airport Extreme.  Is this normal or have I perhaps got a duff battery?