Do I need to replace the motherboard

[mosifekam]

I bought a Asus AS-870-PRO Desktop PC in Apr 2011 and paid for extended warranty.
PC could no longer access internet in Dec 2012 - Network Adaptor need to be replaced.

Spoke with the PC repair technician engaged by the warranty company and was told that there are 2 options :
1) install a new network adaptor
or
1) replace the motherboard with a different model-the motherboard that come with my PC is no longer being manufactured

The technician's advice to me is to just "add the network card to minimise change"
The warranty company will call me today to go through the options.

I would be grateful if someone could advise me on which of the above options to take.
Many thanks in advance.
I have backed up my file using Acronis True Image.

Appended below are some reviews of the PC that I found online:

[nicole_powell]

Yes, replace it to avoid unnecessary problems in future.

[Selvass]

yes replace the motherboard that is the best option for the future
Surprise Solutions

[ORLOVA]

You should never replace the motherboard of a computer unless:

You are experiencing a technical problem and are instructed to do so by a technical support specialist. This would most likely happen if the computer is being used frequently for a business.
Your current motherboard does not satisfy your computing needs (upgrade).
You are refurbishing a non-functional computer and cannot get it to work even after replacing all other components.

In a word, don't do it unless you need to.

[lishmalinyjames]

Yes, You have to change. If not changing to catch trends or speed, a PC motherboard can last for 10 years or more.