Exchange files between 2 computers with 2 different internet connections

[Exxpertul]

Hello everyone, I have the following problem:
I have 2 computers connected to the same hub.Each of the 2 computers has it's mac adress registered to the server, so each has a certain bandwith for internet assigned. There are about 100 computers which connect to this server and on the internet they share the same ip, but internally they have the same class of routable ip's. I have windows xp on both of them. What I want to do is share files between my 2 computers, but at the same time be able to use the internet, with the 2 different connections that I have. I'm not quite sure if I made myself understood. The connection to the internet is made automaticly, with DHCP. The problem is that if I share a folder normally, everyone on the network can acces it, and I don't want that. If I want to set permissions on a folder, I can only do it for local users. For example, if I would like to let only user x from computer y to acces my folder I cannot, because I would need a domainin order to be able to select that user form the dialog box that appears, and I haven't got one.

[antioed]

Just create local users with the same user/password as the users who are trying to connect.

[Kashif]

way is to create FTP servers for file sharing

[TheOgre]

SSH (SCP, sFTP), password-protected webserver directory, rsync, cvs, stunnel, etc.

If they're Winblows boxen, your best bet might be stunnel.