Lets see...
The processor should be fine unless you plan on playing very large games.
The RAM would need doubled since you are running windows XP, other windows might let you squeak past but buying another 256mb stick is advisable.
Your problem is the onboard video card it is currently stealing 32mb of your ram (you really have 256 ram not 224, the videocard is taking 32mb for itself this is changable in the BIOS you can set it up to 128mb-256mb), playing civ4 on a onboard videocard typically isnt possible.
Basically if you have money comming in now and want a new computer then buy one, but simply by buying more ram and a real videocard you can make your computer run like a new one or probbally better.
Heres a few things you might want to look into:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=586829&Sku=ULT30215
$20 for 512mb or ram is a great deal, and ULTRA brand is very good.
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1776106&Sku=P450-8568
$55 for an XFX 6200 with the 256mb of its OWN ram, it should be good for civ4. You would need an AGP slot (you should have one but check anyway), XFX is a great company and this card is not top of the line but should get you playing newer games like CIV4, Half-Life 2, and Doom 3 at medium-high settings...
There are cheaper cards that will do the job but these two offers will give you the most bang for your buck, If I was you I would upgrade you would be amazed to what these cheap upgrades will do for you.
