Setting up FTP for different domains

I have never set up ftp-sites before, and have some basic questions to get started. I have a Windows 2003 server / IIS 6, and run all websites on a single IP using host headers to direct traffic.

The structure on my server is like this:
c:\Inetpub\wwwroot\domain1 (this is www.domain1.com)
c:\Inetpub\wwwroot\domain2 (this is www.domain2.com)
and so on....

I want to make FTP-access with unique username and password for each domain.
Example:
ftp.domain1.com (with username=domain1 and password=password1)
ftp.domain2.com (with username=domain2 and password=password2)

Do I need to use "Isolate User" mode to achieve this?
Do I use the servers static IP address or "All unassigned"?
Any other tips for getting me started here?


Thanks alot for your help!!

Best regards,
Øyvind Isaksen