What would be a good motherboard to go with a quad 9550 or 9450? I would like to go with a MB that uses DDR 3 memory.

if want to get max overclock go with asus - nvidia can not power quads as far.
 
best mobo for single slot is p35, make sure there is a bios upgrade - they inexpensive the p5k wifi is nice as the gigabyte d3
 
if your going ddr3 then maximus or p5e3 is good
 
my 790i is in the mail - hard to say, but the 780i can not power a quad as high as the x38 mobos - they are close.
stay away from 680i - they can not use 45nm no bios upgrade

Thanks for the help, I was looking at the asus board p5e3 because i have a 3870 x2,just in case i want to crossfire it. I have the 680i now that why i looking for a new board.

is there a particular reason you want to go with DDR3 memory at the moment? the price performance ratio of DDR3 is horrible compared to DDR2.

I what to update my computer and I want to get something I can keep for a couple years. DDR 3 memory is what i want, i found this at zipzoom.
http://www.zipzoomfly.com/jsp/Prod [...] e=10008037

You will hardly get any performance improvement by using DDR3 RAM now. It will probably take 1 - 1.5 years before you see any real performance improvement and that would probably require a new chipset.