DriveMaker Freeware mounts or maps an FTP site to your desktop or Windows Server as a drive letter, for example: D:. Now you can use all kinds of different software to access the files on your FTP server just like the files you have on your PC, including the command prompt, anti-virus, Microsoft Excel, Word, etc.
The basic version of DriveMaker is free, even for commercial purposes, forever. (Redistribution is not permitted, however. You need to download DriveMaker each time from the link above on this page). Runs on Windows Server 2008 or Vista and later.
FTP clients require you to download files before you can edit them. Then, you need to upload them back to your FTP server after you're done. Not only is this inconvenient, it may also lead to data loss when you forget to upload your file back to the FTP site. DriveMaker gets rid off this inconvenience by mapping FTP sites to a virtual local drive.