I never cared to find something better than the synchronizer included in Total Commander (formerly Windows Commander), which is my default windows filemanager since ages...
Total Commander is shareware, although you could also consider it as mildly annoying freeware- it has no expiration time, no locked features, and all you get when unregistered is a nagger screen at startup...
Probably the best windows application ever.
www.ghisler.com