There is a Test button on the ReadyBoost tab within the device properties which, according to help I've seen online, should test my drive's speed and display the results and whether or not I can use ReadyBoost.
Well when I click Test, the button disappears, but absolutely nothing happens. No other information, no errors - I can simply click OK to close the window and that's about it. Are eSATA drives not meant to run ReadyBoost?