I tried CoffeeCup Free FTP and Smart FTP. I didn’t like either of them pretty much. While the former has a lot of connection issues, the later ends up taking too much resources all of a sudden on my XP Professional besides the cluttered UI which could do with a redesign.
I’m trying out Core FTP now and it seems to work good. I hope it stays that way.
If you want to use a commercial FTP client, I would recommend Cute FTP.