Thanks everyone for the great input. If I go with wired the only real obstacle I have would be that I need to fish the cable down an 8ft wall from the attic. Not the big of a deal. As far as security don't the routers come with passwords that would keep intruders from trying to hook up to my connection? The router I have in mind has 54Mbps. Would that be enough for gaming? Thanks.
Yes, routers come with the ability to set up a password to lock out your system from those you who don't want to have access.
54Mbps (aka Wireless-G) is more than enough, 11Mbps (aka wireless-B) would also do fine if you are gonna try a wired network.
My whole family uses a wireless network through using routers and wireless cards, it works fine for use especially when you share stuff over your network. If your gonna do head to head gaming through a lan, you should have extra wireless cards or adapters ready. We use wireless-g routers and they work the best IMO.