What do you think is going on on your network?
If you setup wpa or wpa2 (and if you have n band devices you should be on wpa2 because you need to be to get full throughput) and choose a pword your neighbors can't guess your golden. Wep can be cracked in 0-3 minutes but wpa and wpa2 require leased supercomputer time to crack, and even then only if the pword is short/weak.
Just turn on wpa2, change the pword and your good.