If you're using wep, you'll at least have some protection and the casual internet user would usually use another unprotected network.
To crack wep you need a laptop with a wireless card capable of injecting packets into the destination to generate enough encrypted traffic with the unique iv (initialisation vector), and also a fair amount of knowledge and understanding of wep, coupled with the right tools (linux based tools like kismet, aireplay, airodump and aircrack). Then you can collect the encrypted traffic and run the tools against the collected data to beak the wep key. It takes a while if you don't know what you're doing, and even when you think you're doing it right it sometimes goes wrong.
For most people this is way outside the scope of their knowledge so wep should be fine in the home environment. Personally, i'd refuse to use an open link.