I have a SharePoint site set up on one of my networks to service Active Directory users. To be clear, this is a Windows SharePoint Services 3.0 installation running on Windows Server 2003 Standard. It is not an option to upgrade the server or SharePoint version.

Management would like to create several new sites, one for each of a handful of clients. These sites will be used like "dropboxes" or FTP sites so that my company can make large files available to outside contacts, and vice versa.

Here are my requirements:

1. I do not want to have to create Active Directory accounts for each external contact.
2. If possible, I would like to store the external usernames and passwords in a database that I can write a small GUI for so that management can handle adding their own external contacts.
3. Each client site must be sandboxed from each other and from my main company SharePoint site.
4. I would like to keep everything running on port 80 and be able to access the sites as either clientname.mycompany.com or www.mycompany.com/clientname

If anybody has ever done this I would really appreciate hearing about any lessons you learned and suggestions for how to set this up.

Kyle