iPad backup

[Neil 1042]

Does anyone know whether there is a way to control what the iPad backs up? I have installed Cinexplayer (brill app by the way) in order to watch avi prorammes. You add the avi files which you want to view by using the device / apps function. Trouble is I've some 25gb of programmes added and iPad wants to back them all up. Because you can't control this backup location in itunes (it's always the C: drive on a windows machine) it promptly fills up the remaining space on my C: drive. As I already have all the avi files on external hard disk storage I can do without backing them up. Anyone any ideas?