What you need :
1. A laptop/slate/tablet/pad with Intel 3rd generation core (e.g. Core I3/I5/I7)
2. WiDi compatible TV or Projector
3. Install Widget on you laptop/slate/tablet/pad and you are ready to go.

The technology that enable you to transfer screen content to a TV or projector has been around for 6-7 years now, BUT it has been hard to use.

DLNA and AirPlay is probably the easiest to use technologies which people are familiar with.
However, there is a third option called WiDi. This technology allows the e.g. Teacher to walk around in a classroom while showing the content of his/her screen on a remote screen.

Apple delivers this via AppleTV for Mac
Intel delivers this via WiDi for PC

7 things you should know about wireless projection

Intel Wireless Display works on 3rd generation Interl Core Processor.
it runs on Windows 7 and Windows 8

If you have these two in order, go here to install the Drivers* on your laptop:
Intel WiDi Drivers

*Most likely you only need the WiDi Gadget (Step 4)

If you cannot find a suitable projector, what about a 60″ plasma display?
LG 60″ plasma display with WiDi