You should get the pro version of Quicktime (buy it or 'find' yourself a serial number). You can use
Quicktime Pro to export movies to many formats, including a pre-settings for itunes.
You can also use
Mpeg Streamclip (Mac and Windows), that recognizes a lot of videoclip formats that Quicktime might not, to download at:
Squared 5 - MPEG Streamclip video converter for Mac and Windows
Mpeg Streamclip also has itunes pre-sets that can be modified as well.
Having these two together on the Mac, I have found no film/video yet that I couldn't convert. Bet it's the same for Windows.
Good luck.