I know almost all of us has quicktime installed but I would guess that isn't the case with surfers. So, why not make both H.264 and WMV formats and give the choice. If you labled H.264 as for iPod and Mac use, it would probably work well with everyone.
If I have the choice of Quicktime or WMV, I always select WMV. I just found a few examples...
http://at.its.uiowa.edu/digimedia/Hi...Examples.shtml