Windows Vista has introduced a clever new caching system that can take advantage of your existing high-speed storage devices (such as USB Drives and Memory Cards). This should boost performance when performing disk intensive tasks. Some flash memory devices are up to 100x faster than a standard hard disk, so it makes sense to use these to cache common files. ReadyBoost works with SuperFetch to store information that can be accessed quickly from the cache on startup, rather than relying on slower reading from the hard disk. There are several requirements that your flash memory device must meet to be used as a ReadyBoost device: At least 256 MB in size Access time of < 1ms Capable of 2.5 MB/s read speeds for 4 KB random reads spread uniformly across the entire device and 1.75 MB/s write speeds for 512 KB random writes spread uniformly across the device At least 235 MB of free space. It is recommended that you have between 1-3 times the amount of ReadyBoost cache as physical RAM. However, ReadyBoost devices are limited to 4GB max. Assuming you meed the minimum requirements, plug your device in to a USB 2.0 port and wait for a Windows Autoplay dialog box to pop up. Select the Speed up my PC option from this menu. You can then set the amount of space on the device that you wish to allocate to ReadyBoost (you may as well use the maximum possible, up to the 3x RAM recommendation). If your device is not compatible or is too slow, you will be informed of the reasons at this point. Users with low amounts of system RAM (512MB - 1GB) will notice the biggest performance increase, and those with 2GB or more may only notice marginal gains.