1) biostar is like the super cheap mobo. Personaly I never suggest below the Asrock quality. But well since it shouldn't damage anything if the mobo fry in a year or 2 you can just replace it.
2) Rosewill chalanger is a dam good case for dirty cheap: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Won the tomsaware for case <50$, bought 4 of these case for friends and I reccomand it to anyone. I don't mean the one poeple suggested aren't good justw anted to point that option.
3) Buying a 600w+ PSU will give you the option to upgrade your GPU if you ever intend too. Might be a little more money now but would save you more in the long run.