Hi,
You'll need somthing like this for your router...
Wireless Cable/DSL Broadband Router 4-port (802.11G) £35.24
Built-in firewall to protect your Intranet.
VPN support: pass through of PPTP, L2TP, and IPSec. (to control the other pc's)
Plus 1 of these for each pc thats connects, You probably won't need to bother for the one thats next to your cable modem already just use one of the ethernet ports to wire to that (you'll get the best speed as well)
Belkin Network Adapter / Wireless Usb 2.0 802.11g £22.91