A lot of people use VLC but I never liked it that much. I have been using different versions of Media Player Classic for many years. This is what I currently use:
MPC-BE (Ctrl + Up Arrow increases speed; Ctrl + Down Arrow decreases it.)
If you need to install codecs try the K-Lite Codec pack. If you just need a few codecs download the Basic pack. The Standard pack includes basic codecs plus the MPC-HC media player which is also good.
K-Lite Codecs
I used MPC-HC in the past but can't remember why I switched to MPC-BE.
