You did good - spot on
Bad news & good news ....
You are running a RADEON 7000, that will not support T&L, which is why you are getting black terrain (there was an issue of black terrain for other reasons that was resolved for the overwhelming majority of people in Patch V1.52 - dont confuse the two issues).
You card will not run it, its below the hardware spec for the game - its not the old black terrain error
However, the good news ...
Your motherboard will support a card upgrade. It has an AGP 4X slot (AGP 8X cards are backwards compatible dont worry about that), so you can fit a mid range graphics card relatively cheaply. Need to check heat issues carefully, but its fairly straightforward to sort out. The specs of your motherboard are:
http://www.intel.com/design/motherbd/bv2/
You will need those to discuss an appropriate Video Card (go for one with 128mb on board the video card). Be aware that an absolute 100% guarantee that you will run the game post upgrade is impossible to give - as with any PC, not only yours - but the upgrade is essential to have any chance, and I am 99% certain you will be ok after card upgrade, given that we may have to work through some software issues not related to the card.
Hardware Specs for Civ IV:
http://www.2kgames.com/civ4/support_msr.htm
Bottom line - no doubts, go for it and upgrade the card. You have 1Gb main RAM so you should have an average to a little above average performance for Civ IV providing you upgrade the video card
Regards
Zy
If want further advice on a suitable card post again.