This works great. It comes with all required cables and worked straight out of the box. I didn't need to look at the manual. I can now share my wireless USB keyboard and mouse (Logitech DiNovo) between two PC's with this, because of the USB-sharing port. I have had countless failures with other devices trying to achieve this in the past. This one is a success though and it's dirt cheap too (25 quid plus postage)
I plug my wireless USB keyboard/mouse hub into the KVM's USB port, and it gets routed to whichever PC is active. Works perfectly. I still have to make the PS2 keyboard connections to each PC though (PS2 mouse connections not necessary). Because firstly, the PS2 connections provide power for the KVM... and secondly, it seems you can't switch PC's unless the KVM detects something on both PS2 keyboard connections. One of my PC's is a laptop that has no PS2 ports (only USB), but it worked fine with a USB to PS2 adapter.
I did not have to connect a "console" PS2 mouse or keyboard to the KVM at all - however, this means I have to use the button on the KVM to switch PC's (There is no keyboard shortcut if you don't have a PS2 keyboard connected to the box!)
My monitor worked flicker-free for both PCs at high resolutions HOWEVER a control panel tweak was needed: WindowsXP on each PC thought the KVM was a "generic" monitor, and didn't see "through" it to the real monitor. So I got a flickery, wobbly 60Hz default refresh rate at first. I changed the refresh rate in the control panel to higher values (on both PC's), and after that the display was perfect for both - clear and flicker free, no wobbles.
I have to assume it works OK with a PS2 keyboard and mouse too, but I haven't tried that. The USB sharing clearly works well, as does the monitor sharing. If there is a downside, the box is small with many connections sticking out in all directions - some may find this messy or inconvenient. But I rate this 5 stars anyway - because it does a good job while costing very little.