By default, Windows XP comes with a pretty good set of power schemes. But if you're a control freak, you'll really love the Power Saver application that Toshiba ships with its Tablet PCs. You can create an unlimited number of additional power schemes, give each scheme its own icon, and then play around with 20 different sliders and 2 drop-down boxes. And that's just on the most useful tab! On other tabs you can configure power alarms and emergency hibernation settings, toggle power to system devices, and generally do everything possible to eke out the last usable millivolt from your batteries.

Of course, it's also easy to spend more time playing with this application than you'll ever actually get back from it in terms of battery life. So here's some hard-won advice from a former addict on the 12-step road to recovery.

First, work out the number of distinct ways that you use your tablet. I seem to use mine in one of three different modes, regardless of whether or not I'm plugged in:

  1. "Fast" - demos, compiling, and other compute-intensive tasks.
  2. "Normal" - everyday computing, i.e. Outlook, OneNote, or just being a second display for my desktop PC.
  3. "Cool" - browsing, either in bed or during long meetings.

Next, think about what's most important to you in each mode:

  1. Fast - I need maximum performance, for which I'll happily trade off fan noise (and battery life, if I'm not plugged in).
  2. Normal - I don't need blazing speed, but I do want peace and quiet.
  3. Cool - maximum battery life and a cool lap, please.

Now create matching power schemes, using the "Details..." button to tune the power settings for each. The settings are pretty self-explanatory, except for three that interact to affect speed and noise:

  • Processor Speed: well, ok, this one is easy - it sets the maximum processor speed, where more speed equals more battery drain and more heat.
  • SpeedStep Technology: this is Intel's method of throttling back the processor even further. For everyday use leave it on "automatic", which throttles back only when the processor is idle. For demo use, try "performance" (never throttle). And if you want the ultimate battery life, try "battery optimized" (always throttle) combined with "low" processor speed. Just be prepared for a reeeally slowww laptop!
  • Cooling Method: if the processor heats up due to heavy use, it can either turn on a fan ("maximum performance"), throttle itself back ("battery optimized"), or do a little of each ("performance"). These three choices map nicely to my demo, browsing, and everyday computing modes.

The magic settings for everyday computing seem to be high processor speed, automatic speedstep, and performance cooling. With this combination the fan never turns on unless the CPU gets pegged for more than a few seconds - which is generally a sign that I'm doing something wrong…