The instructions on this page:
indicate that windows vista will auto-install the fdti drivers for the board when it is plugged in. One windows 7 (ultimate, 64 bit) the security efaults appear to have changed and it will not automatically download the drivers. you must go tell windows to allow downloading drivers, and then it works.
I just got a Windows 7 machine. How do you change that setting?
You just plug in the Arduino and wait for the driver installation part to pop up. then select "install driver from a folder" then to the directory where you have installed arduino-0021, then select the 'drivers' directory and install!
mine looks like this
I hope it works, though Im using Windows XP.
;D :D :)
Mine self installed the driver, i didn't have to do anything