Will a 15m ethernet cable deliver a good enough connection for my wii?

I can't get very good (or any) Wifi signal in my room we think its because of a the great big copper boiler that's just outside. This applies to my xbox as well but I'm hoping buying the N adapter will fix the issue for that. The wii however presents a complication. Is there any way of boosting the signal that's cheap, reliable and compatible with the wii, like a really sensitive wii compatible wireless adapter dongle or something? Any help would be so appreciated I can't tell you.