MSI ms 6163 pro MB Vs realtek 8139d PCI lan card

[Statesman308]

Bought a Skymaster (realtek8139D 10/100 PCI lan card) today to network my old pc (MS 6163 pro - P3 550e comp) to my new pc. old comp has been working ok put in network card and it lights the 4 leds all red (powering on) and sits like that for ever. Now i thought it has finnally died (now 5yrs old) so i pulled out the network card and it boots up fine, why?? tried adjusting the control panel and the bios, nothing has changed. Changed PCI slot, nothing, and the card does work the network registers it and it lights up.

Does anyone have any idea why this is happening.

Thanks,
Stuart.