I bought the Scandisk Cruzer Titanium U3 4Gb Readyboost in order to use it as the Readyboost functionality advertised in the product name on Windows Vista.
Once I plugged the product in Windows Vista asked me whether I wanted to use the Readyboost functionality and I said yes. Since I had a reasonable amount of memory in my PC, a performance boost was not immediately apparent.
Shortly afterwards Windows Vista locked up and would not give me permission to do anything (no access to task manager or shutdown). I was then forced to hit the reset button).
Unplugged the drive and went to Scandisk website, which after taking me in circles a couple of times told me that the U3 software was not Vista compatible. There was an option to download an U3 uninstaller, which I did but the software could not find my USB drive when I plugged it back in. Next option would be low level format, but why should I have to do this with a product which advertises itself as Readyboost compliant.
Not impressed with software, as a USB flash drive appears to function OK. Caveat emptor, question of Vista compatibility is not obvious on the Scandisk website.