Okay, ive got a 1024x768 13" laptop display and a 1280x1024 19" LCD external display.

Ive managed to get it extending the desktop onto the external monitor okay but it wont go any higher than 1024x768 when extended. Thats a bit naff, as thats the whole point i own that monitor, so i can have room for coding, and have the design document on the big screen. Is it possible under Linux? I mean it should be? It has been on windows since 98SE lol...

Yes, I have this setup on my Fedora laptop using a NVidia laptop chipset, using 1024x768 and then 1680x1050 on my monitor.

Hmm... Thats wierd. I just cant manage it. Im on Ubuntu, but its a crappy intel integrated graphics solution, so i think maybe its broken right now due to the fact the intel drivers have been undergoing a lot of change recently.