about the PCI-E/AGP board there are some MOBOs that have both slots, but the agp slot is called AGR slot and supports only a few agp video cards, you have to see the list..maybe on the mobos manual.. of supported VGAs
with civilization IV i will have to disagree i had an old-budget sempron 2800+ socket A, 512mb and a geforce FX 5200 128mb it was imposible to play it smoothly even on the lowest settings
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