Now here's the problem; according to this forum, the DS requires TX rate between 1-2 mbps from the router. However, the official UK firmware of my D-link DSL G604T router does not provide a setting for the TX rate. As mentioned by Bubbz and Marty_McSly (to whom I'm eternally grateful), an Australian version of the G604T firmware (v2.00B02) solves the problem and connects the DS to Nintendo WFC. After reading through the whole topic, it seems that a helluvalot of people has confirmed that the method works. I could not be more excited to try out the solution for myself.
I followed Marty's instruction step by step, and everything was going well. I changed my PC IP address to 10.1.1.5, subnet mask 255.0.0.0 and the default gateway to 10.1.1.1. I ran the firmware update software, and received a message to change the IP address to the same subnet to 10.48.88.66. I changed mine to 10.48.88.69 as suggested by Marty. In his guide, it worked first time. I wasn't so lucky. I tried to upgrade the firmware several times, but every time the installation would stall at a particular point. The software said that there was FTP timeout and I needed to change my IP address to the same subnet as their device. Eventually I changed my IP address to 10.48.88.88 and et voila! It worked! The installation process was successful and the router has now has the Australian v2.00B02 firmware.
However, I was still half way there. I now effectively have a brand new router and I will need to configure the router to work with Jovian's broadband subscription. One thing struck me dead. I forgot to note down the username and password of the broadband subscription! Oh no, and I thought I was doing so well! After beating around the bush several times, finally I remembered to look in the BT broadband installation box. Jovian's got it hidden under his bed and when I openned the box, the manual told the username that will be used for the subscription. Jovian knows the password, so after configuring the username and the password, I saved all settings and restart the modem/router. Guess what? It worked! Jovian can now surf the internet again and play RO Online. As far as he's concerned, nothing seemed to have happened so he feels... indifferent. I'm happy because now I know how to install an Australian firmware to a UK product (-_-!) and connect my DS to WFC!!! (<-- the most important thing!)
One thing I have yet to discover is all the configuration of the bittorrent download. The thing was always a bit of a pain since I couldn't got through my firewall and establish a 'green' connection with other peers. I had done it finally, Since I haven't got anything to download using the bittorrent, I think I will lay it off to one side for the time being.
Oh yeah! Of course everybody is invited to add me as to their Animal Crossing friend list. My Animal Crossing: Wild World friend code is 0687-8675-XXXX (Contact me if you're interested). I hope to see a lot of invitations soon! ;D
IGN Review of the Animal Crossing: Wild World
expansys.com forum: DSL-G604T and the Nintendo DS discussion
D-Link Australia: D-Link DSL-G640T firmware v.2.00B02