Free SFTP and FTP GUI client for Windows - WinSCP

What is WinSCP?

"WinSCP is an open source SFTP client and FTP client for Windows. Its main function is the secure file transfer between a local and a remote computer. Beyond this, WinSCP offers basic file manager functionality. It uses Secure Shell (SSH) and supports, in addition to Secure FTP, also legacy SCP protocol."

http://winscp.net/