Hi,
You lose loads of bandwidth when WEP is enabled, I don't use it personaly.
The best website I have found for looking at the risks of wireless networking, especially if you have DSL is the famous:
http://www.warchalking.org/
These are the guys who want free wireless networking for all. They target mainly large corporate networks for free surfing, so the risks in a residential area are low.
However the risks you run are A) People will try and use your net resources for themselves, B) Your network gets hacked from out side and burned.
Get a good firewall (BlackIce is V.Vgood) and only let specific IP addresses logon, use a imaginatiive workgroup name and make sure any access rights are password protected.
See ya