I have a linksys router too.But I didnt have any trouble connecting my wii to wifi.I just did what the manual said.Entered the settings automatically and kept going.The connection test was successful...
It could be that you had security on.I didnt and it was easy.Try deactivating it for a while, enter the settings automatically and activate it back.You shouldn't miss.
If still not working check wireless communication settings through your pc, you might find something there.
You could figure out if your wireless is working simply by entering gts from your ds.If you can enter, then the problem is your wii or the settings entered into it...If you cant, then you miss something from the settings of the router generally.(1st is really more possible)
I hope this helped...