FTP-client for Windows, safety concerns

[herbert langhans <herbert.raimund%langhans.com.pl@localhost>]

Hi List,
it might sound OT - let me explain.

I often share files via FTP with my students, friends, family members
and people who I know personally. Then I create an user account, link or
copy the files in their /home directory so they can download them.
Nothing unusual ...

Sometimes people ask me, where to get 'such a program' (the FTP-client)
from - I tell them to pick some freeware/shareware client from anywhere
and install it on their Windows or Apple computer.

The thing I am concerned of is, that these freeware clients could be
easily prepared to steal the password of MY server. And between user
account and root access its not that a big step.

Long story, simple question: what relieable(!) FTP-client for Windows
and Apples should I recommend to my FTP-users? Some full functional
(think about gftp) gui-programm would be the best. Maybe even something 
easy to install, so I can send them the exe file via e-mail ... 

All ideas welcome. Thank you!
herb langhans