WPA is certainly stronger than WEP, but running either one should really be enough to keep your network safe from intruders bro. If someone has to tools to break through WEP, they'd probably get through WPA too; just with a tad more struggling.
You do have a 3DS or DSi though, yeah? Any other sort of DS doesn't have browser capability, last time I checked.
... And you did mean WPA, right? Otherwise, my limited networking knowledge ain't gonna be too much help. >_>;