I strongly second dan's suggestion: it is generally a LOT easier to rent movies (who buys more than a handful of movies??) via iTunes (or Netflix for that matter) than to pirate them, to say nothing of the risk you are subjecting yourself to.
(and before anyone jumps on me, yes, there are a few legal movies out there to torrent ... but seriously what are the odds in this case? Thank you.)
The cost is really minimal (particularly compared to your time and bandwidth), the quality very high, and the gratification is generally instant.
And yes, contrary to what some people claim, I've seen PLENTY of problems that can be traced back to P2P programs, particularly those written in Java (insert standard Java rant here).