Honestly i don't know why the gigabyte is priced so much lower then the asus (but i suspect its the name that your paying for), but most everyone here will agree the gigabyte ds3 is a quality budget board for the conroes. If you can go over your budget though, i suggest the p5b-deluxe cause i think its a great board with no problems (since the last bios release). But alot of ppl here have gone with the ds3, and i havn't seen too many complaints on them.
Since psu companies have put out higher wattage psu's, alot of ppl think they need to get the higher wattage. Trieclipse wrote a great thread
not too long ago explaining why a 600+w psu was really just overkill. My ozc gameXstream 600w should last me quite awhile.
The froton i suggested is a nice psu which should give plenty of power to a dx10 card if you upgrade to one later down the road like i suggested with evga's step-up program.