22 inch! Well, that's a good monitor. 230 watts is not a good PSU. So you'll be getting a PSU and a graphics card.
I suggest the 3,400 FSP Aurum 500W along with the 6790 for 6,300.
That's the best you can get in your price range. The cheapest PSU you could get would be the 3,100 FSP Aurum 400W and $6 is worth the upgrade to 500W...more or less, unless you can spend it to improve your graphics. But the next card up that's better is the 6850, which costs substantially more.
From the link I gave you above, you can judge for yourself whether a 6850 is enough better to justify the price increase. If you can find a 5850 for under 8,000, it is significantly more powerful than the 6790--about 6870 level.