I agree that there were a ton of cringeworthy moments in the prequels. The only thing that's cringeworthy in the OT is watching Luke drool all over Leia and then make out with her.... Yuck. It's funny to think that when Empire came out, the kissing scene between Luke and Leia was probably met with cheers and applause. When I saw the SE in the theatre, that moment was of course met with laughter and groans. Way to go Georgie!

There really were some embarassing moments in the PT. Some of the other really cringeworthy moments for me were......

-Padme's whole Queen getup. Just plain nasty. And the monotone voice she spoke in was really bad.
-Whenever Boss Nass did that really gross thing where he shakes his head and crap comes out. How stupid and childish.
-The whole slavery on Tatooine thing. And pod racing for Anakin's freedom? Really lame. He should've just killed Watto and the hell with it.
-Anakin's "wet dream" about his mother in AOTC.
-Looking at Yoda in Phantom Menace was pretty cringeworthy.
-That stupid scene in Clones with 3PO's head on the battle droid's body's and vice versa. LAME.