I don't like "Decent". :(
You'll have to excuse my language, I'm a bit of a freak when it comes to PC's and always want the best. I have an i7 920, 2 GTX 285's which is a pretty good system, and I'm actually considering some upgrades for myself. I'm honestly not a fan of AMD chips, in fact there's only 1 AMD processor I have respect for and think it worth the money and that is this... http://www.newegg.com/Product/Product.aspx?Item=N82E16819103849
The AMD X6 can actually get pretty close to the performance of a $1000 Extreme chip from Intel. Pretty impressive for the price. The rest I just honestly feel don't compare with similarly priced Intel chips. Also, AMD chips don't have triple channel RAM support which is disappointing. If you know what a RAID setup is for hard drives, dual and triple channel are more or less the same for RAM. If you don't know what it is, well, it makes things run faster =)
Building a good PC is all about making sure there aren't any bottlenecks. You can spend $1000 on a couple high end Graphics cards, but if you don't have a powerful enough CPU then you can't utilize the full power of the GPUs. If you get too powerful of a CPU and not a good enough GPU, it's kind of a waste as well. The ideal thing is to figure out what your needs are, find a budget and build accordingly.
For the GPUs you're considering, I think you've picked out a good enough CPU/Mobo/RAM setup.