As far as I know there are no plugins for IE7 for FTP support. I have be using the Firefox plugin, FireFTP
, since last November. I fined it clean and light. It is also very basic. It sits in the Tool tab in FireFox, so in is very convenient when time to use.
There are many stand alone FTP clients. I like and use FTP Surfer
If you are going to use it for basic services I would use FireFox with the FireFTP plugin.