Thought I'd just post an update, bought one and it arrived today.
Had a bit of trouble getting the PS3 to switch into 720p since the TV i had it connected to at the time didn't support it and the Converter needs a Progressive signal at either 480p or 720p to work (I managed it eventually).
There are some small black bars either side of the picture where it doesn't quite fill my monitor (and I can't stretch the picture on my particular monitor either...) it works fine
Some pics over at
http://fbdragon.co.uk/external/pics/ps3vga/