You can try to
-make a wired connection
-change the signal to WPA, WPA2, WEP, or none
-move the wii closer
Try disabling the SP1 firewall in the WAN Setup tab.
Nintendo has a troubleshooting sectoin for this router here:
http://www.nintendo.com/consumer/wfc/en_na/routers/Netgear/WNDR3300.jsp
If not, try this: http://www.amazon.com/Wireless-802-11N-Network-Adapter-Noteook/dp/B00333AWTA/ref=cm_cr_pr_product_top
or this: