If you want to save money on the graphics card you can't go wrong with a 6600. Other than that I recommend the nvidia 6800.
Corsair ValuSelect memory will carry you just fine on an A64. If you want to OC, maybe look into a higher quality Corsair or Mushkin. Kingston isn't bad either. I use 2x512 Kingston HyperX pc3200.
I forget what the model numbers are, but Asus and DFI are some solutions for mobo's right now right PCI xpress.