want to run to pc's without cables running through house.Have road runner cable.main pc os is ME. grandsons XP .Do I use router or modem? And how do I find out if the pc's have (wireless card) .Thanks Also grandson plays games so needs cable speed.
Get yourself a wireless router with built-in cable modem, which will provide internet access to all connected PCs. As for your question of how to tell if the PCs have wireless cards or not, most PCs don't have built-in wireless cards whereas most modern laptops do. Check in Control Panel | Network Connections and see if any wireless connection is listed. If not, which I expect to be the case, you can get good USB wireless adaptors fairly cheaply which will do the job perfectly well. Since the network speed over the wireless connection will be far greater than the internet speed via your cable connection, there should be no problem with your grandson's games.
make sure you enable wireless encryption so those annoying neighbours dont nick the connection. if you need help with that im sure someone here can help lodore