I don't generally recommend ebay, but it might be the easiest option:

http://shop.ebay.co.uk/i.html?_from=R40&_trksid=p519...

Thanks everyone for your thoughts and assistance. After much deliberation I have decided to turn adversity into an opportunity and have decided to upgrade both processor and motherboard, thus future proofing at least for a while my PC. It would have been preferable not to have had the issue in the first place and I now certainly regret going from a system without any problems at all to one that just refused to fire up and just because I thought I'd add the hard-drive I purchased a while back as I had a spare 30 minutes the other weekend. That 30 minutes has turned into hours of wasted time and effort. Oh well - that's life.

So now have to wait a few more days for the new bits of kit to arrive. Meanwhile I shall thoroughly clean all the fan blades in readiness.

You can flog the dual core intel on ebay. It should have held its value as they're useful for hackintosh machines.