Amazon Music Unlimited Offer: 1-Month For FREE!
canon 5d mark 2 video quality

If you want to see what it should look like when playing it smoothly and you have a decent HD television, plug the camera straight into that with an HDMI lead.
For viewing it on your computer smoothly, as already mentioned, an upgrade might be necessary, perhaps just your graphics card if your lucky.
It's also worth trying different software to view your movies, i.e. Windows Media Player, VLC player.
I had the same problem with my Canon 7D movies. A move to a slightly newer processer and a graphics card update solved the problem and they now play back perfectly smoothly.
For viewing it on your computer smoothly, as already mentioned, an upgrade might be necessary, perhaps just your graphics card if your lucky.
It's also worth trying different software to view your movies, i.e. Windows Media Player, VLC player.
I had the same problem with my Canon 7D movies. A move to a slightly newer processer and a graphics card update solved the problem and they now play back perfectly smoothly.