Not possible to use as a regular computer running windows. There are however cluster based OS like
http://www.kerrighed.org/wiki/index.php/Main_Page
but it will be far from your familiar windows based desktop experience - all you will get is a linux shell and the OS will automatically hop processes over the network to slave nodes. Pretty good for determining protein structures, calculating pi to zillion digits - but not for desktop computing - because not all algorithms are easily parallelizable.
cheers
arun