I just bought a sapphire HD 7870 and maya 2012 is close to unusable with glitches/tools not working properly because it's an unsupported graphics card. Look up Autodesk supported graphics cards for maya on google and go with one of those on the list. They might cost a bit more but they'll save you whole lot of trouble (and stress).
Although someone else on here might know a workaround for getting the 7870 to work... It's definitely a great gaming card though, no doubt.
I'm quite new to building pc's but the rest of your hardware looks okay to me.