This post is actually devoid of factual content as it stands. Please don't take it as an insult, read on:

Media Player Classic uses codec decoders you have installed on your PC, VLC ships with everything it needs to play your videos. In other words, you should not be comparing VLC to MPC, but rather VLC's underlying codec library (from ffmpeg, I believe) to the active codec decoder being used on your Windows machine.

For example, I too use MPC on Windows to get better video - but that's because I have CoreAVC installed and MPC uses it to play h264 content. CoreAVC blows everything else out of the water in terms of performance and quality.

What codec are you using on Windows w/ MPC?