When a computer is playing a video or a DVD, what is handling it, the processor or the graphics card?

I need to know because I want to play 720p videos and sometimes Bluray movies, but some of the cheaper laptops only have a cheaper processor, but an integrated graphics card that may be able to handle it.|||I have been able to run 1080p on a Pentium 3 processor, with a decent GPU (6600gt) it will be fine.

Make sure it has a blu ray reader/writer unless you just plan to watch something like MKV files.|||When you're looking at the laptop, you'll never know what it can actually do unless it has an HDMI port on it. Find out the makes and model #'s of the laptops you want to buy and put them in a question here. I'll be able to tell immediately which ones can and which ones can't.