For your price range for vid cards, I would go with a 7800GT. The GTX is overpriced, and the GT is better than the X8 series.
Since you are gaming, AMD will give you a bit of an edge. If you like ASUS mobos, go with the A8N-SLI Premium. It has a lot of nice features, and doesnt have the problematic chipset fan like the Deluxe has.
From the CPUs you chose, only the 3700 is compatible with the mobo I suggested above. THe 3700 is a good all-around CPU, especially for the price. For about $60 more, you can get an X2 3800+ which is nice for games that are starting to utilise dual core CPUs.
I wouldn't worry about getting Pro. Home has had it's support extended for a few more years. Pro is really only useful if you are connecting to a Domain or actually need the extra options that it offers.
I would get at least a 500W PSU for you system. One like this
would be good for you.
BTW, welcome to TF