I thought everyone rips off O Fortuna. Mitsuda certainly did for a Xenosaga I track. Though in these instances, I'm more inclined to say that they were influenced by Orff rather than ripping it off completely.
Now, Gundam F91.... there's a soundtrack that is damned close to John Williams's stuff:
http://www.youtube.com/watch?v=Jl1DTJjQmrM