also been using a wifi 11g setup for my home network for the past 7 months now...

it will help if you use WPA encryption since this is much more secure... it would also be wise to configure your access point to allow only certain MAC addresses to connect to it but i think you are already doing this (MAC filtering)... my access point logs a lot of intrusion attempts everyday but they all fail to connect to the network...

i'm currently using 2 wired PCs and five wireless devices (2 laptops, 1 tablet PC, 2 PDAs) in my home wifi and they currently share one cable internet connection... i also use this network for some LAN gaming, file and printer sharing between the devices...