SuSE has packages for openvpn and openswan. There also is a kvpn KDE program that will allow you to administer either graphically. I don't know which one would be easier for Windows users to install.
You should still read the vpn howto on the www.tldp.org
website. If a client has Linux, they could use SSH's scp and sftp as well. Simply secure your server and ssh access. The scp and sftp programs use the ssh protocol and are part of the ssh installation.