Please replace the struts. Struts are a key safety component of the suspension. As Jay said, switching the tire will just destroy the other tire, and give you a harsh ride.
New ones can be purchased for as little as $26
each (plus shipping). The book time to install rear struts is one hour each, but if you can change the oil, you can change the rear struts on this car. It's two bolts, and a plastic cover in the hatch area.
http://www.rockauto.com/catalog/emailpa ... ar%2520fwd