I have to respectfully disagree. That codec pack is buggy as hell. It plays some files fine and others give it fits. Try playing a matroska container with it and you will quickly see it's limitations. You can leave the Vista Codec Pack installed, and install the CCCP codec package. When you install CCCP, ttell CCCP to use ffdshow for everything but H.264, under file associations, leave them unchanged, make sure to select Autoload VSFILTER (WMP and MCE support), leave Enable AVI support unchecked, as FFDSHOW does a great job in that department, select RESET ALL SETTINGS, and RE-REGISTER FILTERS, also in setup, be sure to tell it to enable shell intergration and thumbnails for .mkv files. Once you have done this, install COREAVC to handle all of your H.264 content.
Here are two reg keys that will reg all of your extensions for MCE also. Thanks to Toyanucci for the keys. I know it says Quicktime, but it takes care of mkv, mov, and mp4.
http://rapidshare.com/files/8481453/Quicktime_For_MCE.rar
Here is the link for the CCCP package.
http://www.cccp-project.net/
For COREAVC, there a number of torrent sites with it. Be careful though, one of them floating around has the bloodhound viri.
Seriously though, I am know trying to be an ass or a know it all, I was pulling my hair out over all the damn codec issues, if you don't believe me, set a restore point and try it for yourself. Seeing is always believing. I was at the point where I was going to just convert every damn file to DVR-MS out of sheer frustration before one of the moderators at hdbits.org walked me through it. I literally have not found a movie I cannot play now. No sync loss, no choppy video, not a single problem whatsoever. I am playing .ts, x.264, h.264, mpeg2, WMV-HD, DVR-MS, BluRay, HD-DVD, etc.
For reference, my rig is as follows.
Windows Vista Ultimate
Asus PC-DL Deluxe
Dual P4 Canterwood Xeon with hyperthreading. 4 logical procs overclocked to 2.97ghz
4GB RAM
ATIX800 PRO 256MB running component output to HD set @1776x1000 (for overscan)
ATI 650 Pro
ATI 550 Pro
ATI HDTV Wonder
Primary Master 250GB PATA
Secondary Master Sony Dual Layer burner (will be adding XBOX HD-DVD next week)
Primary Sata Intel ICH5 Striped
Channel 0 Seagate 500gb
Channel 1 Seagate 500gb
Secondary Sata Promise 378 Striped
Channel 0 Seagate 500gb
Channel 1 Seagate 500gb
SoundBlaster XFI Platinum
Ultra 650 modular power supply (POS replacing it also. STAY AWAY INMHO)
Hardware is a little outdated in places, but she is built up enough that she holds her own. My current Vista score is a 5.2 due to the fact that I am running DDR400, but with the 4 procs and the amount of onboard cache, I haven't found a game I can't play at high settings, even while I am recording two shows at once with MCE. I am waiting for a good Dual Proc Intel or AMD quad core board to come out before I make the leap to next gen hardware. Nothing better then being able to set the processor affinity to individual programs, and the idea that many logical processors, along with dual GPU's and possibly a Physics card is very appealing. :)