yes there are some that will use NT authentication like IIS. WS_FTP comes to mind, it uses SSL encryption. Also you may want to look into
Vshell, which is a SSH2 FTP server.
Bear in mind though that encryption will slow down your transfers. it may be a good idea to just encrypt the control port and not the data port, that way your passwords stay safe but yous till get good transfer rates. Also, all clients will need to use a compatible SSH2 client rather than a standard ftp client like bulletproof or cute.
Cuteftp is also working on a SSL Ftp server.
-P