I've not used WS FTP, so no real help in that regard. You could go with something like
Rumpus: About Rumpus for browser based FTP. Or you could educate your clients and inform them of some of the free sw available for FTP clients. Like Cyberduck, etc. I used to have an FTP running on a XServe, and we always pointed customers to a free client software, and walked them through install, and upload + download the first time. After that most folks were off and running.
