I don't know about going with an nForce2 chipset motherboard. I have one, and it only gives me problems when combined with an ATI video card. So if you ever plan to use an ATI video card, then don't buy an nForce2 motherboard.
I would recommend this board. A7V600. It's a KT600 Chipset, so it should out perform the KT400A boards, and it's got some nice features included with it, all at a relative cheap price. About $88-$100.