In the last few versions of Windows, you had a number of options at your disposal for turning off your computer. You could use the Shut Down option to turn off the system entirely, which saved power but forced you to close all your documents and applications; you could put the system into Standby mode, which preserved your work and enabled you to restart quickly, but didn't entirely shut off the machine's power; or you could go into Hibernate mode, which preserved your work and completely shuts off the machine, but also took a relatively long time to restart (faster than Shut Down, but slower than Standby).

I think it's safe to say that most users were confused by these options, particularly by the (subtle) difference between the Standby and Hibernate modes. By far the most common power-management complaint I've heard over the past few years is, "Why can't Windows be more like a Mac?" That is to say, why can't we turn off our machines instantly, and have them resume instantly with our windows and work still intact, as Apple has done with OS X?

The new answer to these questions is that Vista is heading in that direction with a new Sleep state that combines the best of the old Standby and Hibernate modes:

• As in Standby, you enter Sleep mode within just a few seconds.

• As in both Standby and Hibernate, Sleep mode preserves all your open documents, windows, and programs.

• As in Hibernate, Sleep mode shuts down your computer (although, as you'll see, it doesn't quite shut down everything).

• As in Standby, you resume from Sleep mode within just a few seconds.

How can Vista preserve your work and restart in just a few seconds? The secret is that Vista doesn't really shut off your computer when you initiate sleep mode. Instead, it shuts down everything except a few crucial components such as the CPU and RAM. By preserving power to the RAM chips, Vista can keep your work intact and redisplay it instantly upon waking. Don't worry, though: Vista does make a copy of your work to the hard disk, so if your computer completely loses power, your work is still preserved.

To use Sleep mode, open the Start menu and click the Sleep button. Vista saves the current state and shuts off the computer in a few seconds. To resume, press your computer's power button; the Vista Welcome screen appears almost immediately.