If you're upgrading everything I'd ditch the Athlon II for a Phenom II x6. Yeah a lot of people here will tell you the i5 is better ad nauseum, but I really like the Phenom II and it helps keep things under budget. For the motherboard, don't settle for anything less than the 990FX, it's easily $50 cheaper than just about any Intel equivalent and you have an upgrade path for when the Bulldozer / FX series are available.
As for the video card, I love the Radeon 6800 series - very easy cards to work with, and the GTX 560 are really good as well.
I'd also upgrade the PSU to a Corsair or Antec 600 watt at least, depends on what your primary use is. I wouldn't touch a cheapo, no-name PSU with a 10-foot pole.