TV and a plasterboard wall

[Maxf]

I want to put a TV on the wall in my flat in a pretty specific place, and as far as I can tell this is just plasterboard, with no wooden beam behind.

The TV will (at a guess) be about 25kg.

What would be the best fixings to use? I understand you can buy some which screw into the board and open out on the other side, creating something more solid to screw into - any idea what I need?

[Maxf]

Thanks - search never works for me. The second link is useful... not sure what chump posted the first one though