I recall from a previous thread you need quicktime for itunes or some such so quicktime alternative is probably out:
http://www.free-codecs.com/download/QuickT...native_Lite.htm
The 1080p I see there most likely means issues with H264 files (the alternative above does have some playback support for h264 in it), try installing a new FFdshow tryout:
https://sourceforge.net/projects/ffdshow-tryout/ or alternatively CCCP:
http://www.cccp-project.net/ and enabling decoding by FFdshow.
Oh and I am sure are aware but you can disable error reporting (one of my pet peaves with recent windows):
http://www.xp-antispy.org/
Edit:
too slow again.
disabling directdraw may work but can also push usage through the roof, it also points to a codec issue.