Doncha just love these people that recommend cooling solutions that cost more than some mobos or CPUs (that's $40. + a fan + shipping)...

Besides which I don't think the clearance in the Aria (height) will allow the Alpha anyway. Have you ever actually measured the clearance you have? That would be a useful bit of info for us to have.
. OTOH, if you think the Alpha would fit, then this (at about 2.75") would do you just as well:
Spire WisperRock IV or similar, and you'd have some $$$s left to have some Mickey D's. If not, then look at the Thermal integration V77L, but you would have to get a Zalman Fanmate or such to control the feisty fan...
.bh.