There are a few wireless encryption types, and it depends on what router you have and which encryption type you chose upon setup....
WEP is one form of encryption, and the newer ones are more secure.
There used to be alot of network hacking when wireless first came out, but now that it is everywhere I don't really feel its all that important to make things so incredibly secure, but I guess it all depends how much you are concerned with having the latest most secure WiFi in your location. And what you have at stake when choosing a form of protection.
I run WEP at my house because I really don't have neighbors, and I don't have alot of people parking on the road or hanging out in my woods to steal my WiFi...

YMMV