I understand… thanks for the input.
Enemy Territory and a firewall?
Qraft… Here’s what might help you out, I haven’t tested it myself, but it’s in RtCW’s FAQ and I believe it applies to WolfET
http://www.rtcwonline.com/dummies/RTCWFAQ.htm#multiplecomputer
Tell me if that worked 
Qraft, if you can ping servers and browse the internet, then your Router is working properly. Ask around your area and see if you can borrow someone elses router, to prove that your DLink has issues w/ ET but other routers will work. I suspect Smite is correct, and that it is the particular model you have, borrowing one will prove that.
Really sorry you got a shite router, ET is the best game I ever played. Just think of buying a new router as the retail cost you would have payed for ET in a store, had they not released it for free.
GL man, at least your post will serve as a warning to anyone looking to buy a DLink router, now they will know to avoid that particular model, Di804.
One last suggestion I didnt see posted yet,
If your freinds PC has windows XP or 2000 installed, put your 2nd netowork card in his rig and enable internet connection sharing. Its very easy and might be the best workaround for your problem. You can use the router as a hub. The PC sharing the connect will need to be on for you to also be online.
If you are not sure how to do this, post agian and I will walk you through it. There may be a few issues getting this to work, but based on your posts, Im sure you can handle it.
Good Luck