Do you have a DVI to VGA adapter?
Maybe it would work, I mean, plug the adapter into DVI out of your mobo/graphic card and the VGA cable from this to the monitor
These adapters come with almost every dedicated graphic card...
I don't really know if it would work, but my brother uses a Sapphire HD 7750 and it's connected to an old VGA monitor with this adapter... (on Windows 7, but I don't think this is OS dependant)
I did purchase one, apparently there are multiple dvi hookups? The adapter I have does not fit in the dvi port of my motherboard. It does, however, connect to the dvi port on my ASUS 550ti card (which wont even boot). I finally got full resolution (ironically trying to get my 550ti to work) and it looks better. I did notice that there are artifacts of red color on the right side of the screen when I open the notifications. the dock works fine, opening/closing windows works fluidly, and minimize in the dock nicely, but opening the launchpad has issues, and when it is open, the dock is grainy and flashes when i mouse over.
Also, when the computer shuts off the monitor, it goes grey and has white squares.