Network problems

I've had various problems intermittently with my home network. I have a PC running XP which connects to the Internet via broadband and is always turned on. All the other PCs in the house connect to the Internet though that. Every so often the connectivity within the network is lost. I've spent ages trying to work out how to fix it. I've just fixed it and all I did was to run the network setup wizard on the central computer to configure it so that it appears to be the same as any other PC in the network (i.e. it connects to the Internet via the network). Then restart. Then rerun the network setup wizard to configure the central PC back as the one which connects to the Internet. Somehow it seems to work.