[Not convert as in steal i.e. convert a car

]
I have many guitar video clips, some in Windows format, some in quicktime & others in Real Media, & now thanks to Google Video & You Tube some in flash format (.flv).
My Nero software claims to be able to convert Quicktime to Windows but doesn't, but I do have Movie Shop which does but I am still working out how to do that. I would like to be able to convert all the above types to Windows format as that would be the easiest for me to edit and put on a VCD/DVD.
Does anyone know how to convert any of the above formats to Windows format, for free?
Looking forward to your replies
Dan