OSWeekly.com has posted a how-to about boosting the performance in Windows Vista. Here's an excerpt:

Users of Windows XP have often witnessed a sluggish system behavior just after booting their system, after a fast user switch or after lunch. This is because Windows XP executes background tasks, such as anti-virus application and other utility applications during such periods of inactivity. During booting, the operating system loads all the programs in the startup folder and until that is done, your system is pretty much useless. Executing such applications takes up a lot of physical memory (i.e. RAM). When you want to use your computer, Windows has to reload RAM with your data. This process takes a lot of time and results in small periods of system sluggishness.

SuperFetch resolves this problem by intelligently preloading RAM with the applications you are most likely to use at different times. It tries to learn what applications you use at different times and prepares your computer to execute those programs. It prioritizes user programs over background tasks. Windows Vista also does many of the loading process in the background so as to give you the control over your computer much faster. This helps to increase system responsiveness.

Windows Vista takes advantage of the nonvolatile flash memory integrated in most new hard disks. These hard disks, called hybrid disks, are intended primarily for mobile computers. ReadyDrives writes most of the data to this flash memory. The advantage of this is many folds: less hard disk writes means less wear and tear and greater life of the hard disk (plus increased battery life on notebook computers). Since retrieving random data from flash drives is much faster, it reduces the time it takes to boot up, sleep and resume from hibernation. Above all, it increases disk reliability.