Just a quick post to clear up any confusion on the ReadyBoost compatibility list.  It turns out that devices which don’t quite meet the Vista storage spec may still show up as ‘compatible’ in Windows Vista (and in this list). 

Dave Pryce emailed to point out that the minimum spec for ReadyBoost is 2.5MB/s read & 1.75 MB/s write, while Microsoft’s ReadyBoost usage guidelines say that for a device to be listed as Enhanced for ReadyBoost it must do around double that – 5MB/s read & 3MB/s write (based on 4k random reads and 512k random writes).

You probably already know that not all Flash devices are created equal, but it’s interesting to also note that devices that don’t quite meet the spec are still deemed compatible in Vista. My recommendation is to look for read/write rates wherever they’re quoted in the ReadyBoost chart – a faster device should result in a more noticeable performance gain.