My previous setup was as follows:

[modem/router]------[switch]+------ [pc1]
                            +------ [pc2]

I've just moved and had cable installed and I no longer have the option of running a lengthy LAN cable from the router to the switch to provide network and internet access to the two PCs.

The cable company provided 2 wireless N USB adapters.

What do I need to buy to plug into where in order to restore the network to its previous state?

PC1 dual boots Windows 7 and Ubuntu 12. PC2 runs Debian 6.

Edit:

• USB adapters - Netgear WNDA3200
• Switch - TP-Link TL-SF1008D 8 port Ethernet switch
• Cabling - various patch cables cat5e rj45
• Modem/Router - pretty standard cable company job - wireless

Intention is something like-

[modem/router] --wifi-- [some-new-hardware or perhaps to pc1] ----[switch]---[pc1/2]