I have a very similar card, it is identified as: 3D Rage Pro AGP 1X/2X. I opened up Hardrake and took a look at the video card settings. BTW, I'm running Mandriva 2006, I also ran 10.1 for about a year. I'm not seeing any of the problems you describe, worked well under 10.1 and 2006.
When I looked under Hardrake the card is identified as : Vendor 4098, Device ID 18242, Sub Vendor 4098, and Sub Device 132. I have Module ATI Mach64 Utah loaded. I think there are several modules you can try.
The only other thing may be the settings you have for your monitor. I'm using a Philips 107T. Monitor settings can cause problems too, so have a look at them also.