ATI Radeon 9200

I have an ATI Radeon 9200 and downloaded the newest driver to get mafia not to freeze. This helped not freeze the game, but when I go to the porperties of my desktop there are two screens displayed "hp f1503 Flat Panel Monitor on Radeon 9200" and there is also (Default monitor)on Radeon 9200- secondary. The hp f1503 goes from resolutions 800-600 pixels to 1024-768 pixels. The Default Monitor u can set from 800-600 pixels to 2048-1536 pixels. But u can only set it to the Hp f1503 resolutions if u set it to the Default Monitor one it goes back to the Hp f1503 and it doesnt let u choose the Default Monitor one to adjust the quality to a higher degree. I want to play Mafia with a better resolution and this is why I want to change it to the second one which has a better resolution.
Thanks