ReadyBoost is a technology only available in Windows Vista which allows a custom USB drive to be used for caching in order to boost performance of the PC. It basically takes some of the active system files that are randomly called upon and caches them on the flash drive. ReadyBoost employs a logical system on the drive to make access very quick and the end result is that requests for data from the customized USB drive are said to be 80-100 times faster than a hard drive. To use this, you just plug a compatible custom USB drive into a Vista-powered machine. The AutoPlay dialog will provide an additional option for speeding up the system. Select that option and you will get a Properties dialog window for the drive with an extra tab for ReadyBoost. Windows will test the drive to see if it is up to specs for ReadyBoost. For a USB drive to be ReadyBoost ready, it needs to be over 256MB, have an access time faster than 1 ms, be capable of 2.5 MB.s reads and 1.75 MB/s writes. It is also recommended that the USB drive be 1-3 times larger than the amount of system memory. So, for example, I have 2 gigs in my desktop. I should have a custom USB drive that is at least 2 gigs in capacity.