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.
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:\arduino-0021\drivers"