I've worked the problem out a little bit further. I found that when I use the video selector and change it from PAL to NTSC, if I boot the xbox and then turn my monitor off and on again, it will display the dashboard, as if my monitor is reinitializing and perhaps has an issue with doing this when I turn the Xbox on initially. I tested another smaller old monitor I had laying about and it worked without needing to turn the monitor off, so that at least tells me that my monitor is doing some weird crap and wont work until I turn it off and on again to get an xbox display. The thing is though, I still can't use PAL and get it to display anything other than a completely scrambled image.... very odd.
Also, now that I have seen some games running on the key digital VGA Box, I've noted that some are awefully dark in appearance and so much so in some cases like Halo in different areas that It's almost impossible to achieve a good image without knocking the brightness way up so you can see certain things better, which ends up washing out all the colours... not happy with that. Perhaps it will work better on a different monitor and give better vibrancy. Some games looks just fine, but there are a number of games where the colours lack or areas are too dark where there are dark colours being used like blacks... GRRRRRRRR can anything just go smoothly for once? please!!!!! heh