The best one I've used is Windows Media Encoder. I don't know the Vista setup, but for XP you have to update your system to Microsoft Framework 2.0.
http://www.microsoft.com/windows/window ... fault.mspx
For me it's
really slow so I stay away from it. The only benefit for me for WMV is that you get thumbs, but I've found that if you do a lossless re-mux .mpg to .tp and change the extension back to .mpg you get thumbs. Weird, but it works.
Just a note: You're never going to please everyone. If you post wmv then the Mac guys will have issues. Some people can't play high bitrate AVI's because their PC's are too slow. Some of them don't have mpeg-2 codec. Just post whatever format is best and easiest for you.