There are probably a numberof ways to do this depending on what you already have.

I'm going to assume you have no network in your house and all the PCs are not connected.

Assuming your broadband modem connects to your PC via USB (or is internal) then

• adding an Ehternet card to your attic PC
• buy a wireless access point (with the right 802.11 spec to match your existing Centrino notebook)
• Add a wireless card to your sons computer - you can get internal PCI cards, but if you don't wantto open up his machine then I believe you can get USB adaptors.

Once that's wet-up you can use Microsoft Internet Connection Sharing on the attic PC (assuming it's at least Windows ME I think - 2000 or XP better) which will allow the other PCs to connect to the Intenet. It will also let all the machines talk to each other - which is great for music if, like me, you've copied all your CDs onto one of the machines. This solution does mean that the attic PC has to be on all the time anyone else wants to use the Inernet.

Wit a little more money you can get a device that contains the ADSL modem and the wireless access point all in one box. There boxes usually also contain some fixed wired ports as well. You can connect your attic PC to the access point directly. The other machines have wireless cards as above. Note that these products usually contain a basic firewall as well and are generally considered more secure than Windows. It also means you can turn the attic PC off and still have the other PCs connecting to the Internet.

Hope that helps - give me a shout if not.
Pete