Well, you can use a browser in console, type links
Then you can try getting the drivers from ATI's website for Linux.
Good Luck doing that via the links browser(s)
I really am amazed it's not working "out of the box" though.
I know you think that using your old card sounds archaic and not worth the work, but at least you could possibly narrow it down to either your card OR your monitor, instead of the possibility of both.
Also, you can configure X out of X. Use xf86config or possibly drake has something better for it? Post on mandrake's boards, the guru's there might have an answer for, but I can't seem to get a link to it for you. Anyway, poke around www.mandrake.com
and you probably will find the boards faster than me because I am half asleep anyway.
Good Luck, and don't get too worried, alot of the power of linux is in the command line anyway you know
Don't let it frustrate you to the point of hating Linux though, give it a rest, and come back. It's these hurdles that make you know your system better than you did yesterday.