Allow network users to view website without password

First off I am completely new to configuring IIS. I've only ever used it to test my own php at home.

Secondly I've searched these forums for the solution and although I've seen problems similar, I cannot find the answer to my particular situation.

I'm developing an intranet app at my workplace. It's a simple program but I need to restrict access to it. I was going to use NTLM so that only users on a certain domain can access the app. I had it running on another machine with apache and everything was fine.

I decided to start doing upgrades and testing from a local copy on my machine so I installed IIS.

My problem is this: I can access the site by http://localhost.
I can access the site by http://my computer name.
When I try to access the site by http://my.ip.add.here I get a windows login prompt. If anyone else on the network tries to access the page they get the same password prompt.

How do I disable this prompt while having the client/browser negotiate NTLM with headers?

If you need more information, let me know. I'm totally new to IIS and don't quite know what more I'd need to tell you to solve my problem.

Version IIS 5.x
Win XP Pro

Here is the error message if I cancel the password prompt

Fixed the problem!

I did what I should have done in the first place, INSTALLED APACHE!