Notes - "When you connect a supported flash device to your system and choose the Speed Up My System option, Windows Vista runs a quick performance test to see if the device meets minimum standards required for ReadyBoost. These results must be consistent across the entire device. If any of these tests fail, the drive is rejected. You can look up the specific performance results for yourself. Open Event Viewer (Eventvwr.msc) and click the Applications And Services Logs category in the console tree on the left. Under this heading, click Microsoft, Windows, and ReadyBoost. Under this latter heading, select Operational. The log entries in the center pane include performance test results for both successful and unsuccessful attempts."