Two PC's one monitor

[crestfa11en]

One VGA to find them, One Monitor to bring them all, And in the darkness bind them

Geeky puns aside I'd like to connect two PC's one monitor, what is the cheapest solution under £10, a KVM Switch or a D-SUB splitter although the cables would need to be very long?
I have no need two run two computers at once, it's merely to save me the energy of switching the VGA input from one computer to another, every time I my sister needs to use the old PC.

The monitor in question is an old LG L204WS-SF 20 inch Widescreen TFT.

Screen Size: 20"
Screen Resolution: 1680x1050
Response Time: 5ms
Brightness: 300cd/m2
Contrast: 2000:1
Main Specifications:

Product Description: LG L204WS-SF - flat panel display - TFT - 20"
Device Type: Flat panel display / TFT active matrix
Colour: Silver
Dimensions (WxDxH): 46.6 cm x 22.6 cm x 38.4 cm
Weight: 5.5 kg
Diagonal Size: 20" - widescreen
Max Resolution: 1680 x 1050 / 75 Hz
Colour support: 24-bit (16.7 million colours)
Image Aspect Ratio: 16:10
Response Time: 5 ms
Image Brightness: 300 cd/m2
Image Contrast Ratio: 2000:1 (dynamic)
Signal Input: VGA
Compliant Standards: TCO "03, DDC-1, DDC-2B, EPA Energy Star, ISO 13406-2
Power Consumption Operational: 80 Watt

It as a D-SUB connection the graphics card is a GTX 670 DVI with adapter.

Side note must bug my sister to upgrade her monitor 1680 x 1050 with a GTX 670 madness.

 

[crestfa11en]

THIS IS NOT MADNESS THIS IS A 2007 MONITOR!!!

Side note need to find something more productive to do with my time.