4wd: I wouldn't recommend MPC-HC.. I repeatedly found videos that wouldn't play in it, or would only have audio or stuff like that.
I've used it for almost a year however I always have ffdshow installed for encoding anyway, so I set MPC-HC to use it for decoding.
Plus I rarely view anything other than MPEG2 or 4 - if it's some other format it gets deleted, (eg. Flash based crap), or if I really must keep it, (unlikely), then it gets transcoded to MPEG4 so it can play on my standalone.
I don't know what it is with the latest version, 1.1.604.0, but it just wouldn't last more than 20-30 mins on the internal codecs on my system. 188.8.131.52 however, runs fine on it's internal codecs.