From their website www.coreftp.com
Free Windows software that includes the client FTP features you need. Features like SFTP (SSH), SSL, TLS, IDN, browser integration, site to site transfers, FTP transfer resume, drag and drop support, file viewing & editing, firewall support, custom commands, FTP URL parsing, command line transfers, filters, and much, much more!
I found this one on Filehippo.com. The download was about 3.3MB. It installed very quickly with out the need for a reboot (at least on Vista). I am using this software to connect securely to some of my Linux servers over SSH. The drag and drop functionality is very helpful to quickly copy a file to or from your desktop for quick editing.
It has a very familiar two window interface to drag and drop files from one location to another. It also has a simple way to add and edit sites that you need to connect to.
I haven't tested every feature of the program yet but the only real issue I did encounter was that the help file would not display, however the online version of help is available. This may be an issue with Windows Vista and not Core FTP lite. One other small item I found was that if you hover your mouse pointer over the icons in the programs tool bar there are no tool tips. This makes it a bit more difficult to use the program efficiently until you memorize what the icons mean. There may be way to turn on the tool tips but I could not find it.
If you find any other issues please post a comment and let me know.