VGA input for laptop

I visit several people week in week out to diagnose various PC faults.

I'd find it really useful to be able to connect a pc to my laptop to use the screen on my laptop as the desktop monitor (to gain access to desktop when monitor fails etc).

Tried to come up with various ideas but the only one that seems like it might work is a PCMCIA card with a VGA input.

Does anyone know of such a thing?

Tried several searches but I just keep finding tv capture/tuner cards.

Any ideas?

Thanks in advance

I wanted to do something similair btu again failed, something I did find was that there are several software packages out there that will let you use a laptop as a second monitor if its connected to the main PC by a crossover cable.

http://www.microsoft.com/windowsxp/u..._multimon.mspx

Has some tips on doing it.