It's still running Windows even in 'standby' mode so will still be consuming battery power. You could try using the 'hibernate' mode instead, which uses no power at all (because it effectively shuts down) yet still boots into Windows really fast from the 'memory' file on the hard disk. This is the preferred option for longer absences. Standby is only intended for short 10-30 minute absences.
In Power Options set the laptop to 'Hibernate' when the lid is closed, instead of 'standby'. Many Vista owners do this anyway even for the power button since Vista boot time is ridiculously long.
Be aware also that if you use the laptop from the mains power for extended periods, you should fully charge the battery and remove it. Failure to do this when on mains power for long and frequent periods will eventually overcharge the battery and shorten it's useful life --- it will become flat faster than you expected because it can no longer hold it's charge. I failed to take this precaution and now my battery lasts for no more than a few minutes even when the charge-meter says it's 100% charged.
It's a problem that gets gradually worse when it first starts --- you only get maybe an hour from it when you expect two hours, until eventually you get only minutes but the charge meter doesn't reflect this. So be warned!
Edited by Grandad Phillip, 07 December 2008 - 02:50 AM.