Read up Descartes for a start Stu (the same guy behind Cartesian co-ordinates - fucking awesomely clever man) and then I'd recommend reading up on Greek philosophy as well.

If you're not into all that then a good starting point would be 'Sophie's World' by Jostein Gaarder (a kind of beginners guide to the different philosophies throughout history).

I agree with some of the posters on this thread though - the first film was really good and the last 2 just sucked ass.

Andy