Thanks for the feedback guys, unfortunately it doesn't help.
Apparently there are 3 types of DVI outputs:
DVI-I = Digital & Analogue Signal
DVI-A = Analogue only signal
DVI-D = Digital Only Signal
I had no idea that there were differences so when I saw that the new comp puts out DVI-D, I assumed that's what I had been using on the old comp too.
After checking I now know that my old one is actually DVI-I and I'll put money on it that Glenn & Blurker's are too.
Thanks anyway guys, but I think I'm stuck till I can afford a new digital ready screen.
*EDIT*
Sorry Dunno we posted at the same time!
You're right, I'm screwed!