Guys, it's all very well having a laissez faire view on wireless security, but it's not good practice to omit details to those who don't understand.
Why is it you guys are the very same ones recommending firewalls? Most people will get on fine with the built-in Windows one and don't need advanced configuration and protection. Yet, because of your own views on the nature of network security, WEP, which is by technical definition a completely broken technology, is fine? Sorry, but it makes no sense, and it's not good practice.
WPA doesn't have a significant overhead on modern networks when it comes to internet connections. I have a 10mb cable connection, and that's exactly what I get via wifi. On a 54Mbps 80211.G network, WPA's overhead is transparent for a net connection like that - and this will apply to everybody except the fastest 50Mb internet users (who should have wireless N anyway). So that argument doesn't hold any water whatsoever.
Also, it's not just people out the front of your house you should be worried about. I live in a flat (not uncommon in the UK that one) and I pick up quality signal of no less than 5 other wifi networks. It's not just desperate people that would have access to mine, it's savvy people who don't want to have to pay for access.
By all means, use your broken encryption or leave your network open. In the context of ADVICE for other people, retain some parity between it and your advice on other areas of PC security. Internet security is recommended, and the WiFi alliance recommends security. So you should recommend it too. To me, your opinions are simply something that I disagree with, to someone like sprayer, it will form the basis of all that they know on the subject, and they don't have the luxury of disagreeing or knowing better.