Ok...
First of all I will refer you to
http://www.westernunion.com/info/faqSecurity.asp for some information about Western Union. Western Union should really only be used for transfering funds to someone that you KNOW and TRUST. Once it is in their system and the other party has the required information, they can divert the transaction to some other location (so that it's harder to be tracked).
I would STRONGLY advise AGAINST using Western Union for any transaction on the internet.
Additionally, in some countries, they are not as "Strict" with the ID portion when receiving the money. They do not necessarily need the MCTN or YOUR name. The name is just something used to reference the account. ID's are easily forged as well, especially in those countries that aren't as strict about it.
I would then INSIST on a Legitamite escrow company.
http://escrow.com is one and ebay actually has several listed (at the bottom of
http://pages.ebay.com/help/community/escrow.html ).
If you chose to use an escrow site... DO NOT click on the links in the messages. Type them in your browser directly as the addresses can be made to look like they are legit when really they just direct you to a forged fake (Look-a-like) site.
I hope this helps you to make your decision