Welcome to LQ !!
For the RH boxes, make sure you have an FTP server installed, most problably you'll have wu-ftpd pre-installed, but just check.
Also, go to /etc/xinetd.d/ and edit any ftp related file, e.g. wu-ftpd, and make sure it is not disabled.
If you have any firewalls installed, put a rule that allows FTP.
For Windows 2000, go to Add/Remove and expand IIS, you should see an FTP server there which you need to install.
I don't think win98 comes with an FTP server, so you can go to somewhere like download.com and get yourself a nice one.