So much more to say about the sublime Mario Kart DS, but for now, I felt some technical advice would help Google out a lot.
If you’re having problems connecting to Nintendo Wi-fi Connection through your Netgear DG834G router - as in, your DS can’t see your wireless access point, even if it’s public, insecure, the works - it’s worth upgrading to the latest firmware. You can download that from the “support” page on the Netgear site for the router. Once you’ve flashed the firmware (remember to do it via a wired connection, to avoid bricking the router), you should find the DS finds the access point (be it WEPed or not) first time.