It's an OK deal. The 6GB you should probably drop one stick when you get it since AMD doesn't run Triple Channel, but dual channel. Plus you won't really need that much ram, 4GB is enough and the speeds will be optimized since it'll be dual channel.
As for the motherboard, can you find out the motherboard model?
At max, how much are you willing to spend?
The machine is actually a solid starter machine. I think the case would need to get replaced, the PSU as well. But other than that. Not much else. Other than also adding the discrete card.