1. Get CCCP & install it
2. Get CoreAVC
3. Go to CCCP settings and disable FFDShow's H.264 decoding
4. Play files in MPC
If it still doesn't work, your laptop is just way too slow. One way to speed up playback is to turn deblocking off from CoreAVC settings, which will basically double the decoding speed, but it also creates some quite visible blocking in H.264 videos.