According to Microsoft, its new Sleep mode combines the fast resume rate of Windows XP's Standby mode with the data protection and low-power consumption of XP's Hibernate mode. When it enters Sleep mode, Windows Vista stores the contents of system memory to the hard disk, just as Hibernate did. It also maintains the memory state for a period of time and then automatically progresses to hibernate when the battery charge or settings dictate. Microsoft's name for the transition to hibernation is Hybrid Sleep. By leaving the system memory up at least for the short run, Sleep facilitates a much faster resume behavior.

The hastening of Vista's shutdown and start-up processes is directly related to the new Sleep mode. That's because the new default turn-off process is Sleep. On a desktop PC whose BIOS properly supports the new Sleep mode (I have computers purchased in 2003 that do), the screen turns off immediately, the hard drive works for a few seconds and the power light goes off somewhere between the five and 15 seconds. Vista comes back on almost instantly, in about one second.

Windows Vista's new consumer-electronic-like on/off button on the Start menu.

All of the above describes the way desktop PCs work with Vista very well -- and I like it. But I've found that the notebook PC experience is less obvious, less beneficial and might be confusing. On notebooks with Vista Beta 2, Hybrid Sleep is turned off and the Power Options setting of Hibernate after 18 hours is turned on by default in all power plans. When I tried to work this way, I found that my notebooks were running in what appeared to be Windows XP Standby mode, chewing through their battery charges much more quickly than I had expected. Had I done that in preparation for air travel, I would have been disappointed to discover that I had used up something like 30 percent of my battery charge before I got to work. It's probable that today's notebook hardware just doesn't support Vista's new Sleep and Hybrid Sleep modes properly, however. My guess is that notebook hardware developed from the ground up for Vista will see notable advances in battery charge life and user convenience.