For E2180 : P35-DS3L or P45-DS3L
For Q6600: Any ASUS Gigabyte P45.
Imo, I wouldn't trust a Biostar as I had a few of their boards die on me.
If you plan on gaming PLEASE get a different card. The 8600GT is cr@p. Not sure about the prices where you live but you should be able to get a 8800GS/9600GSO for ~$60-80.
PSU is fine.
Imo, get 2*2GB or a single 2GB. I recommend Crucial, Corsair, OCZ, Patriot, G.Skill.