Not all flash drives are readyboost capable. I will say however, that in the long run, you would be far far better off just investing in another 1-2GB of RAM if your system supports that much. Readyboost is a temporary stopgap type feature at most. Even with USB 2.0, it's still several hundred times slower than actual RAM, and is probably only marginally faster than using swap space on a hard drive. On a laptop it might have some minor battery saving functions as well, if it reduces hard drive use. Still, RAM will do that too, and it won't wear out anywhere near as fast as a flash drive will.