If I were you, I'd have a look at the Phenom II 810 or Phenom II 710. They are competing with the Q8200 and perform around the same or better, but are supposedly priced slightly lower. Pair it with a 790GX motherboard.
Gigabyte 9800GT 1GB <---Is this a good choice?
The 1GB of VRAM isn't going to be worth it for a 9800GT. If you can find an HD 4850 for the same price, go with that, it's a better performing card. If not, go with the 9800GT 512MB or the HD 4830.
What PSU are you going with?