Do you want divx as in the codec or divx for the "container"?
If it is the former I personally like Xvid, there are loads of command line encoders and loads of frontends too (I have not used Dr Divx since its about 2 years before its previous incarnation died but I understand it is a somewhat general purpose app).
If it is the latter can I advise against the divx container, sure it plays OK with the conventional AVI splitters but for the features it confers I strongly suggest moving to MKV.
Try virtual dub to begin with and then consider moving to a frontend if you find it has too many features:
http://www.virtualdub.org/index.html
It may take a bit of tweaking to get along with vista (it sometimes does not play well with aero) but it is a solid app.
I am not sure about the status of frontends on vista but a quick trawl of the doom9 forums should turn up something:
http://forum.doom9.org/