Craig:
In my focus testing and field research, limited as it may be, I have found that wmv responds differently to PC users according to their browser and Windows OS. It’s been my experience that wmv is not consistent over the multiple Windows OS platforms and often requires plug-ins which many people have no idea how to install.
I agree with you about QuickTime; I only offer it as a paen to Mac users (of which I am one). Flash, on the other hand, seems to have universal accessability and I use it as my first choice.
Jamie