No expert here, but I can give the generalities: ReadyBoost uses the storage available on a USB Flash stick like a cache in order to speed HDD I/O. Basically it allocates data the system determines as likely to be accessed, and stores it in Flash memory. So when a program needs said data, it's faster to access than having to go to the Hard Drive. So if you don't have some flash memory installed, it's not enabled. The rules of thumb I've seen are (1) you want around 2x system memory and (2) once you have more than 2GB of the aforementioned RAM the benefits of ReadyBoost are minimal/nonexistant. http://en.wikipedia.org/wiki/ReadyBoost