Several graphics cards that have released over the past few years have included converters in their boxes. You may want to see if you have one.
Are you sure your LCD has no DVI port at all? That seems really weird.
I know peeps aren't made of money, but just as a thought, the BenQ
1680x1050 is down near $250, and the Dell E207WFP
is ~$275. Actually, those may dip after Xmas. My roomie mentioned a lot of stuff goes on sale in the weeks following. (I mentioned how crazy the sale crowds were when I was hunting for a PS3 on 'Black Friday'.)
My concern is that even if you get a converter and can connect to such a screen (one which only has VGA) that it's tech would be old enough that it would have a lot of issues with gaming (ghosting, etc.)