no, you will have to install them on the 20Gig drive, to play them. you can access the files, change/modify/move, but will not be able to run them, because they must be installed on the OS that is loaded into memory, and that is running. Think of it like this...
if you just purchased a new chevy truck, and turn the key to turn it on, your not going to start the camaro in the garage. you can see it, you can get in it etc... but you wont be able to turn it on using the truck.