Also, save this file: mplayerc.ini as it will be needed so you don't have to reset all those fabulous shortcuts.
MPC does not play HD such as .mkv files as far as I know. I'm guessing VLC prob does.
The thing about VLC, altho it plays more files, it doesnt have much in terms of shortcuts for play control like up 5 sec, back 5 secs, slow, frame advance ect.
For HD I usually use Nero which plays about everything but which is so clunky an interface. Not sure if VLC will play HD and .mkv as I havent reinstalled it since I had to reformat. (boot sector became f'd up from a browser hijacker, at least I think that caused it, anyhow suddenly couldn't boot, no matter what I tried) (reminder: get "bootvis" now)
A guy told me that would have booted me up..