Quicktime for Windows & MP4 playback.
Here's the windows Quicktime download page but read the rest of this page first.
http://www.apple.com/quicktime/download/win.html
WMV's caught my attention many years ago because of their quality compared
to the MPEG's and RAM's of the era.
They remained my perferred clip format until January of 2006.
By then, my disgust with Windows Media Encoder's limitations led me to move
to the superior quality and clip creation control of QuickTime MP4s. I have
tested and used QuickTime 7.0.x on Windows 98 SE and Windows XP Pro without
problem. The XP machine dates from over three years ago.
Take a look at the thumbnails and text below for some of the things I learned:
You do NOT have to allow QuickTime's free player to take over playback of any
other file types! (See #3 below)
You can download JUST the QuickTime player . . . Not the whole QT & iTunes
package.
You can set QuickTime to play ONLY MP4 files.
If you choose to upgrade to QuickTime Pro (about $29.95 for the code-key) Quicktime
becomes an Editing and Exporting utility.
Using QT Pro "cut & paste," it's easy to create and export your
own custom cut vids with LOT's of export options. Or, just trim down any one
clip to contain exactly what you want.
1. High quality demands large file sizes as well as a reasonably fast machine
and adequate RAM. Especially since I "cut" the clips at the same size
as the original footage.
Here is a full scale example cut from digital footage.

2. Even my older XP machine can play two or more MP4s at the same time, including
audio/dialogue only MP4s.
3. To prevent Quicktime player from screwing with your other players, you can
set it to play ONLY MP4s as is explained in the pic below.