Well we should note is that the 9200 is a DX8 (No shader abilities) Videocard and that the X1600 is DX9.0c (SM 3.0 abilities) which is the reason the game isn't working basically your 9200 doesn't know how to render the game. Not to mention the X1600 is 2X+ the speed of the 9200.
Best I can think of for PCI -> http://www.newegg.com/Product/Product.aspx?Item=N82E16814131082 if your in america. This is the HD2400Pro DX10 (SM 4.0) one of the best still available for the regular PCI slot, but otherwise I would seriously consider doing an overhaul of your computer you don't need a super computer, but buying a parts that cost less than 500 would get you a system about 5x the speed of the optiplex and play demigod and most other new computer games nicely. Not to mention possibly lowering your electric bill.