We are moving things around our house, and that means bringing my large desktop PC and my wife's similarly oversized PC into the same room.  We've got a long desk where both PCs will reside side by side.  The problem is that the room has very few power sockets on the wall.  On the wall we have the PCs against, there is only a single wall socket.  On the opposite wall there is a double socket and two single sockets.  However, the desk won't work on that wall, and the other two walls of the room are already occupied.

I'm wondering whether the power draw on a single wall socket will be too much.  Is there a way to work out the power draw/capacity of the socket?  The equipment that we will be using on that socket includes 1xPC (650W PSU), 1xPC (760W PSU), 2 x LED monitors, 1 x powered speakers (25W RMS), 1 x stereo (70W+70W RMS), and one inkjet printer.

If the single socket can't handle the power draw, then we have the short term option of running an extension cord from the opposite wall around the room but that's not ideal.  It would be better to have an electrician replace the single socket with a double socket.  How expensive would that likely be?