I haven't used ftp with Windows 7 yet; but I have configured it on server 2003, vista and XP, so i'll try to help.
I think the first question is - does the ftp work locally? (I just want to rule out router, gateway and local firewalls and make sure that port 21 or whatever you are using) is not blocked.
If it opens locally, we can then troubleshoot externally, if it doesn't work on the local network, we'll troubleshoot IIS.
In CMD (well this has been a while :P)
1. OPEN COMMAND PROMPT
2. type 'FTP yourftp.yoursuffix'
(note - no need for ftp://)
3. It will ask for your user name - type it in
4. It will ask for your password - type it in
You are now connected.
5. typing 'dir' will give you a directory (like dos)
BTW - ftp's will open directly in windows explorer if you paste the link in or change to windows explorer once it's connected via ie (see pic's)