If you're planning to implement a Web App and using a Server other than Apache, then I strongly suggest giving G-WAN a try.
Linky:
http://gwan.ch/download
They say instead of making your software more resource heavy why not optimize it. That's G-WAN team motto. Also, I can't test it since I would have to use Linux for it.
On a side note DRT uses
http://www.dotnetnuke.com/Resources/Downloads.aspx
You can try it here:
http://www.dotnetnuke.com/Intro/Free-Demo-Site.aspx
Posting this in M&A since I have a lot of threads and I can't move back and forth. So, it's a bulk them here and then I can add more content in later or you can just edit them up and add stuff.