SEMI-IGNORE THE ABOVE POSTRight, I've had a positive development..
I took my box to a friend's house (who has decent broadband -- I've just moved so cable isn't installed yet, been using dial-up) and updated the dashboard, even though it said it was 5960 already. I entered XB Live and it said I needed and update, then it downloaded and installed it. All's good.
I then tried to install nDure, with the Basic Installation -- and it works!! At least, the install works. When I reboot, I still get the blank (black screen) after the Xbox logo. But at least the thing is installed.
Therefore I presume the only remaining problem is with the fonts, which Krayzie mentioned above. Can you point me in the direction of some solutions? I've scoured the documentation for the nDure (1.1 and 1.1.1) packages but I can't find anything.
Any help much appreciated!!
PS I tried specifying the 5101 fonts but that didn't change anything. Judging by the message ('make sure you pick the right fonts for your kernel') I don't want to try the others in case it messes something up, unless I get expert advice to do so.