Can't make network card to work on Win98SE

Hi! i am from argentina, my english is not very good but i try to explain my problem the best posible i can.

I have an older NCR computer (model 3501) and i have modified it to have a CD-ROM and Hard Disk drive (before that the machine only has one IDE power conector for one device, CD-ROM or Hard Disk but not the two at the same time) i use it for music and DVD movies but i can't make the on-board network card to work on Windows 98 Second Edition. The system detects it as a "AMD AM2100/AM1500t and compatibles" and it ask for irq, dma and address for the network card because it has problems with other devices and i select other values but it don't work so i select the conflicting values and deactivate the other devices and again it don't work.

Now i don't have idea of what to do and i don't have a free pci port for another network card (the only two PCI are ocupied with a Sound and Video Card)