In all my readings about cracking WEP the general consensus seems to be that it can be cracked after 30-50 million packets are captured. So mnchur is technically correct when he says that on a small home network it would take a while.

As an example, my network has 650 users. Trapping packets entering/leaving the network gets me around 750-1000 packets a second at peak times when I can figure there are probably 100 connections active at any given time. I would consider that "normal" activity insofar as there are few big file downloads or transfers taking place. So, rounding that off you are looking at 10 packets per second per machine. so sniffing 30 million packets from a single machine working 24 hours a day would take about 34.72222 days - more than a month. Looking at it more reasonably the liklihood of the machine working 24 hours per day is low. More likely to see around 4 hours per day on a busy home machine so you need to factor that in giving you a figure in the region of 6 months to gather the minimum amount of data to have a chance of cracking the WEP. I'm guessing that 30 million packets is for a weak key. If the key were stronger then you would need closer to the 50 million packets. In that case we are pushing a year of packet captures to crack the WEP. That should be enough to keep the average skiddie off your WAP.