Chris,

you might want to investigate using a PPTP or IPSEC VPN as well. This would allow remote sites to simply COPY TO or SELECT INTO TABLE into a specified folder on a server in the main office. Or you could simply drag-and-drop using windows explorer. The stream is fully encrypted, unlike FTP that requires extensive tinkering to make it secure.

There are quite a few other benefits for this- for example, remote sites could use the e-mail server at the main office without having to open POP ports in the firewall and your interoffice e-mail would then be inside the encrypted stream, unlike normal smtp/pop mechanisms that transmit e-mail in the clear. Staff would also be able to access documents in shared or personal folders on your main server without exposing their work to snoops, and you can run a VOIP network to give you a PBX that spans all your locations- so Jill in Sydney can transfer a call to Bob in Perth by just dialing his extension, the phone then rings on his desk with no additional telecom charges.

It's not a "programming" answer but it is a logical one, especially since you can run a very reliable hardware VPN for a reasonable price- e.g. check out http://www.shopbot.com.au/p-16634.html