Video card not recognized

Ok i bought this new dell Vostro 200 desktop. it has a 2.33 Ghz Intel Core 2 Duo processor- 3 Gigs of RAM - 160 GB of HDD. Windows Xp pro Sp2 it has 2 PCI slots one and 1 16x PCIe slot and (a 8x PCIe slot i think) Ok it came with intergrated video. I bought a ATI X300 SE HM PCIe video card. i inserted it and the cooling fan works but no video and my computer doesnt recognize it, not even in device manager. so i installed the drivers and the driver setup said there was no hardware compatible for the drivers. So then i had a i had a ATI VisionTek 9250 PCI video card and tried to install it the Vostro and the same happened. Nothing would recognize it. i know for a fact that the VisionTek 9250 video card works because it is in another computer right now and working fine. So can anybody tell me what is wrong. i really need this becuase i need multiple monitors display.