Multi-display

I am using a Dell GX1 pc with an ATI on board video. I installed another video card, NVanta and then another one, S3 Virge. The OS is Windows 2000 now. I upgraded from Windows 98SE. You name it and I have tried it, including contacting MS, Dell and ATI as well, nothing has helped. I keep getting the error code 10 “device cannot start”. I really need to be able to use 2 monitors to speed up my work and our IT dept has no solution either. Help!