I got it, and when i go to play the DVD, a clock comes up with the second hand moving, I'm guessing because it's loading, but it too slows down quite a bit, just watching the second hands stop moving around, so it must be the DVD player if it isn't even playing it and it's messing up.
The CPU usage is up to 100% after closing all applications. either my processor isn't fast enough (i think 2.67 isn't that bad), or the DVD player is taking up so much CPU to try and read the DVD (probably).
I'll probably end up buying a new DVD player. Thanks for your help guys, and great idea to try the nVidia decoder. I would've never thought of that.