I prefer the program alltoavi, which can be downloaded here:
AllToAvi Home
The program is dated to some years ago (~2006). I have runned it and have experienced some trouble with it. Make sure you have compatibility mode and run as administrator turned on. With that, there isn't any problem. The installer doesn't need to run with compatibility mode.
Now, it isn't a 64 bit program but I'm pretty sure it will work fine. The program is pretty quick though it takes maybe 10 minutes to learn how to use it.
(Are you desiring avi files because you know windows 7 can natively support avi files? If you really have any other file types, there are codecs that you can use

. Sure, they aren't as good as the native codecs, but at least they can work. Thumbnailing them can be a chore, but if you know how to configure it correctly, it shouldn't be difficult.)