Hi,
which OS on an identically configured laptop would offer the longest battery life? Vista v.s 7 v.s XP. assume all current drivers.

thx

Short answer: Depends.
Long answer: w7 isnt out yet, using RC1 or RTM versions a few tests have been done that ive read. The consensus is better than vista, but the amount varies alot. It could end up being better than XP, about the same, or a bit worse. Either way, its unlikely to make a massive difference in normal use.

The OS is not as important as drivers if you have the right drivers for your device then the OS is not important .
Then it depends on how many programs are working in the background I guess the worse will be an antivirus this is the reason I don't use windows the other reason is that is to expensive .

Win7 and Vista have superfetch and drive indexing enabled by default, which will affect battery life. They can be disabled, however.

WinXP can also have Desktop Search installed, which will index the drive as well.

Overall, WinXP will get you a slight improvement in battery life, but not significant enough to outweigh the benefits of a newer OS. Personally, I'll go for Win7 when it comes out, but my systems all run Vista now anyway (except my WHS).

Definately not Vista. Now that we have 7 to compare it to, nothing is best on Vista.

provided aero's off i should imagine vista to be better than xp when set to the power saving plan

in the beta 7 when set to low power plan i noticed it turns off aero affect when you unplug it, can't remember if vista does it, but i imagine it would.

one of the things about vista was its battery life, all indexing and such should turn off when the computer is on battery unless you've set it for high performance.

I'd honestly be surprised if xp gave better battery life, unless your running less than 1.5gb of ram and vista needs to page to the harddrive all the time