Well, I thought I had it fixed. I did a clean format of the two machines that were having disconnection issues.

It seemed great for about an hour or so...and then poof there goes another d/c. I log in again on that char, hit follow, and bam another d/c right away.

The /follow post over on the WoW Bug Forum also has others still having d/c issues. So, thankfully it isn't just me. I spent 9 hours today troubleshooting and trying to figure out what the problem is on my end. I think this still might be a server issue...I just cannot figure out why it is only happening on specifically two of my machines out of the 5.

Sigh...what a long day

Edit:
Today the disconnects are still happening on 2 of the 5 boxes. I think I am going to have to call it quits. I have done everything possible without sinking more money on this project. I guess all I can do is wait for blizzard to respond.

If anyone else has any other ideas, let me know. I have spent 10+ hours trying to troubleshoot why this is happening on only a specific 2 of my 5 machines and I cannot pin down the issue.

I have tried the following on the 2 machines:
-Complete format and fresh install of XP
-Tried different NIC's
-Tried recommended settings on the NIC's by Blizzard
-Tried connecting directly to my router rather than going through a switch first
-Tried connecting alternatively through wireless
-Tried disabling all addons
-Tried other things that I can't remember right now..

Update:

I tried one more thing today that may be the answer to the problem. From what I noticed, I would usually disconnect in an inn or other enclosed area. I then noticed the FPS on the two disconnecting would be at 130+ while in an inn or enclosed area. The FPS on the two not disconnecting were sitting at <60 in the inn.

My theory: Such a high FPS is causing more frequent updates sent to Blizzard's servers and causing the disconnections.

I turned on vertical sync on the two machines that were pushing 130+ FPS to limit their FPS to my refresh rate (60). Since all machines now have a cap FPS of 60, I have not yet had a disconnection in a few hours of running around.

So, if you are having issues with disconnects please try limiting your fps to 60 by turning your refresh rate to 60 and enabling Vertical Sync and Triple Buffering under Video Options. Let me know if that helps. I will continue doing testing today and make an update if my theory fails