I believe the MX-2 and AS5 are about the same in performance. Also, a dual core can be better than a quad core, more cores isn't always the way to go. WHat do you plan to do? Maybe I can help you. But do answer your question directly, I believe this: http://www.microcenter.com/single_product_results.phtml...
I would suggest geting a Intel Core Quad Q series i think you can find it on e bay not with high price its like 30-40 bucks not shir you should check it out anyways and you can get a a good cooler for the 30 remaning dollars
one review said he had a problem with the motherboard
I thought when building a new computer you just put them pieces together and install drivers etc .
why the problem ?
Motherboards receive updates to their BIOS over time, these updates come for many reasons, one of them to add support for new processors. A new motherboard usually has the latest BIOS available for it, but it is possible to get one that's been siting on a shelf some where for long enough it has an older version of the BIOS.