Actually, gamestop used to sell a usb thumb-drive that could access ps2 saves on a memory card (read and write) without any extra software. I'm not sure how it worked. I can't seem to find it anymore, though.
*EDIT* found it :http://store.yahoo.com/i-software/114799.html
*EDIT* found it :http://store.yahoo.com/i-software/114799.html