Need advice on Web access for customers

I have been asked to research a project. We want customers to be able to follow a link from our Web page that will allow them to log in and enter in some criteria, and retrieve a report on thier information. Our thought as a start is a separate computer separate form our LAN. What we have at this point is a small network with an NT server and RS6000 with AIX-Unix, behind a router/firewall with a DSL connection to the Internet. The data is on the RS6000. What do we need to accomplish this?I am puting a higher amount on this question to be able to accept multiple answers. What Hardware, Software?
I am leaning toward a Linux Web server.
Dennis