Sapphire HD6870 1GB.
If you're getting a 460 might as well get a 6870. 6870's
better.
An Aurum 400 will do. It's efficient and perfect for your
needs.
Like I said, since you're not going to overclock, get the
P8P67-M instead, and a CM341 casing.
Sure, it's small but it does cool a whole boatload better
than a CM430.