What u need is a combination of a DSL Router and Wireless Access Point.
This piece of hardware will be connected to the incoming line, and establishes a wireless connection to your PC/Laptop.
Here's the hardware u need:
1x Wireless Router/Access Point (preferrably 54MBps standard)
1x Wireless Network Adapter (54MBps Standard)
What barnad/make u go for depends on how much money u planned to spend. I'd suggest equipment from either LinkSys or Netgear
1x