As many of you have discovered by now, isis.unc.edu no longer allows standard ftp access for uploading and downloading files. Instead, you have to use SFTP. WinSCP is a good, free sftp client for PCs, and both fetch v5 and fugu work for Mac OS X.
However, if you have previously connected to isis using fetch or fugu prior to its reconfiguration this spring, you may get an error stating that a connection could not be made to the sftp server. You may need to update your known_hosts file with an updated host key. If you use fugu there is a tool to do this. Go to the Fugu menu and select Preferences. Click on the Known Hosts tab, select isis.unc.edu and delete. A new key will be automatically generated the next time you connect. You can also edit the known_hosts table by hand. Using TextEdit go to File/Open. In the Search field enter ~/.ssh, and then select the file known_hosts to edit. Highlight the text for isis.unc.edu, delete it and save the file.