Regarding the YouTube like application topic

To continue this conversation,http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1364666&SiteID=1&mode=1

This is going in the direction of WPF/E so I post my question also here:

Thanks for your extensive replies, they have really been of help.

When thinking of using WPF/E (or anything else for that matter), I stumble upon another question.
When users upload their video, whether it being avi, mov, mpg, dv, mpeg4, etc.., it has to format to wmv(for wpf/e), how do I automate this process, and should it happen server side or client side?

Thanks alot!

Tobias