I was too busy to read these posts yesterday but I have been involved in a similar discussion elsewhere. The answer seems to be about specific codecs. not the general soft applications. QT uses codecs which are not available/ supported on Windows (yet?). I say "seems to be" because this is what I've been told. I have not had the opportunity to check this out myself yet. But I just bought a PC (it's still in the box- literally) and I hope to get to the bottom of this as I will be working in a business where it is imperative that I work cross-platform. I will report back as soon as I have a more helpful answer. In the mean time here's an interesting link: http://support.microsoft.com/default.aspx?kbid=316992&product=w98#34 This is linked to a specific anchor, but I think the whole page is interesting. Carl