Just a little FYI follow-up that may help others when looking at similar devices.....
Having now tried all the options on my "bargain" it's blatantly obvious that it's an analogue widescreen PC monitor/TV updated with digital inputs (DVD, Freeview and HDMI) "bolted on" but without paying adequate attention to the firmware and integration of the digital signals.
I suspect many other models on the market are quite similar.
The HDMI input, which I thought might be handy for a PC with DVI output, has similar limitations to Freeview and DVD and it's impossible to get a picture that has the correct aspect ratio, or even to fill the screen properly without either a small border all round or losing the edges. Furthermore in HDMI mode you cannot get an external sound signal fed to the inbuilt speakers via any available input, so you need separate speakers. This is a bit weird as both DVD & Freeview obviously do have sound.
However, in analogue mode as a TV or PC monitor (with speakers) it works fine (also from SCART or CVBS inputs). It's actually a pretty good widescreen VGA monitor which I'm now using on my Windows 7 x64 RC1 test system.
Also, the DVD has it's own separate configuration menu that has all the options (screen shape etc.) that you would get on an external standalone unit. So you can even set it to 4:3 (but not 16:10 of course
).
In fact if you set the DVD to 4:3 and the main display to 4:3 you can actually watch a widescreen movie at the correct aspect ratio - on a postage stamp in the middle of the screen with a large black border.
Hopefully this will give anyone looking at a similar system a few things to check.