If you get the retail boxed cpu, try the standard heatsink first. Some of the high end amd heatsinks are pretty good. And see if Asus website recommends any specific memory for the M2N board. I got some email from chiefvalue. Prices for some dx10 cards have dropped below $200. They have 2 brands of the 8500GT for less than $100.
The 7700 "flower petal" cooler will be quieter but otherwise not enough better than the stock cooler to justify its purchase.
Try the stock cooler first. Use the Asus Cool&Quiet program to drop cpu frequency, voltage and fan speed automatically.
The HyperX memory is unnecessary with an X2 6000+. You will not be overclocking this one, so just get standard DDR2-800, save some money and call it a day...