By your speed stest results it looks like your modem is from comcast? If it is, this is your first problem as they lock the bandwith on their own modems.
I would get the beta update for the 4500 and sync the time with your pc.
Take your computer out of DMZ, not a good idea.
Turn game fuel back on.
The router should have WOW in it as an application. those ports as well you would put in special applications, this will help get past the firewall for those particular ports as well. turn off spi and dynamic fragmentation.
Make sure your pc firewall is configured correctly for the game as this will slow you down greatly as well.
You may have to create a gamefuel rule for this game.
As for the modem you can go to bestbuy or circuit city and purchase a Motorola cable modem, works great and opens the bandwith right up.
Aslo look at your logs and internet seeions when playing or logged into WOW, this will give you some idea of anything you need to change.