Rosewill RNX-N150PCx PCI Desktop Wireless-N Adapter for $7.99 Shipped
Rosewill RNX-N150PCx PCI Desktop Wireless-N Adapter for $7.99 shipped after code EMCJNJJ28. Here is a screenshot for your reference. It works with 802.11b/g/n protocols and is a pretty inexpensive ways to add wireless connectivity to a desktop instead of running wires.