E210882 MOTHERBOARD & GEFORCE 5200 COMPATIBILITY PROBS

HELP IM TRYING TO UPGRADE MY DAUGHTERS DELL DIMENSION 3000 TO HAVE BETTER GRAPHICS, THE MOTHER BOARD DOES NOT HAVE AN AGP PORT SO I OPTED TO USE THE GEFORCE 5200 PCI VIDEO CARD, SINCE THEN I HAVE HAD NOTHING BUT PROBS, NOT WITH  VIDEO BUT FOR SOME REASON IT HAS AFFECTED THE ONBOARD LAN, I CANNOT CONNECT TO THE NET VIA MY GATEWAY, WINDOWS SHOWS AT AS CONNECTED BUT IT FAILS TO REGISTER WITH GATEWAY WHEN I TEST IT. I REMOVED IT & ALL WORKED AS NORMAL, I INITIALLY BELIEVED THE CARD WAS AT FAULT BUT AFTER CONNECTING IT TO A SONY VAIO MACHINE  WHEN ALL WORKED FINE I NOW KNOW DIFFERENT. CAN ANYONE PLEASE SHED SOME LIGHT ON THIS AS IM DESPARATE TO GET IT TO WORK.

CHEERS

SHAUN