Is this the computer in question:
http://h20564.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c00347879
If so that is a 15 year old server.
On a brand new board no one really replaces damaged items like northbrige or lan chip because the parts plus labor really quickly surpass the replacement cost, not to mention the large risk of something going wrong during the de-soldering process. On something as old as that motherboard you are not even going to find replacement parts as production of those parts would have stopped 10 years ago.
If this is some legacy computer for non-windows 7 compatible hardware that is detrimental for the business, then you have to understand that really expensive replacement parts are par for the course. It is simple supply and demand and at this point supply is just above zero. Thus your only option to get a motherboard that will work with your current hardware is to buy one of the ebay ones.
If this is the scenario where your business function is reliant upon some legacy hardware-software then you ultimately need to research and migrate to a modern solution. The underlying question is not how much the upgrade costs, but how much money not doing the upgrade will cost in the event of complete equipment failure.
If your 15 year old server is just in use because of upgrade costs, and not because you need windows xp to support your legacy hardware/software then just replace the server At this point the cheapest desktop in Walmart could do laps around that dinosaur, so dropping $300 for a used 15 year old motherboard in this circumstance is just sillyness.
I know that this is likely not the advice you wanted to get, but this is my professional advice that I would give to any client/employer.