Ok, here's the deal. I was confusing a few different connections. We have and 802.11a (WPA2) network as well as an 802.11g (WEP) network. When I was looking at my laptop I saw all the WPA stuff and assumed it was the same for my n800. However, I then disabled the 'a' interface on my laptop NIC and saw that it automatically connected to the 'g' WEP network. I then checked the properties and see this:
Security Type: 802.1x
Encryption Type: WEP

I then found a doc on our IT web page that shows how to configure a Windows Mobile phone to connect to the wifi 'g' network. Here is the piece that concerns me:
===================
Authentication: Open
Data Encryptions: WEP
-This Key is Automatically Provided must be checked/selected
Select Menu -> 802.1x. Configure the following:
-Use IEEE 802.1x network access control must be checked/selected
-EAP Type: Smart Card or Certificate
===================

So... it appears I am on some sort of crazy WEP/802.1x auto provided key system. From the internal docs I've read, it appears that Windows Mobile 5/6 phones seem to support this out of the box.

I'll try manually configuring a WPA connection and setting the "manual username" as you suggested tomorrow, however it seems pretty clear to me that we are indeed on a WEP network.