I like flashfxp. It is not free but reasonably priced and you get lifetime support and upgrades. I think i paid about $25 for it and I couldn't be happier with it. Check it out:
I've been using filezilla for quite a while and don't have a problem with it.
Also if you're in a pinch you can use the built-in command line client in windows. Just open a command prompt and type "ftp". You can type "help" to get a list of commands.
Filezilla for normal use. I was using the built in command prompt with batch files for a while but have since switched to AutoIt for my remote monitoring project. I also use the Filezilla server version.