Wylide36/dave that Video card you have choosen there is ancient, I actually didn't think you could buy AGP cards anymore lol. Your motherboard and processor are far better than that video card is and I would highly suggest spending another 30 bucks on the video card which will take you all the way from at 7600 GT all the way up to a GTX 550. I think the 7600 GT were made back in like 2005/2006 and 4 years is a long time for video card improvements/development. The Power supply you choose is a little expensive IMO and you can find 'name' brands such as OCZ 600watt power supplies for about $50.
I would suggest check out the computer part page here listed below. There is a moderate gaming computer setup that costs about $850 that would be perfect for video editing (and gaming if you wanted).
How to Build a Computer - Part Selection
If you decide to stick with your own build, I would just suggest saving some $$ on the PSU and buying a little bit of a better video card, you dont need a GREAT video card for simple video editing (video generation is a different story), but the 7600 GT might have some problems with higher resolution videos.