I tried to cut corners and hold the new area rug down with carpet tape.  It really didn't work.  So I bit the bullet and got these carpet pads which turned out to be a very good investment.  They make the rug much softer to walk on, and give it a real "cushy" feel.  And they keep it from bunching up or moving around.  So I'm glad I got them, and on sale, too. Would definitely recommend.