Wierdly, it doesn't advertise itself to the world as being a 1920x1200 capable monitor, even though it clearly is - so Linux had trouble with it without custom hackary.
I found a really neat tool for windows that gives you the EDID values from all the monitors ever plugged into a windows box - it can be found here.
Then, I plugged these values into a neat X modeline generator, here, and came up with two modelines:
ModeLine "1920x1200@60" 210.68 1920 1952 2752 2784 1200 1224 1236 1261
ModeLine "1920x1200@65" 236.18 1920 1952 2848 2880 1200 1224 1237 1261
The second one, although bang on the 82kHz maximum sync frequency, was noisy - I think 'cos of the KVM I have in the middle of the cable, but the 60Hz one works a treat.
Yey - linux on my desk at work - again.