Which K7N2 is it? I had (my 7 year old son has it now) a K7N2-L from MSI with a Barton 2500+ that I used quite happily with my 9700 pro, x800 pro, and a borrowed 6800 GT.
Worked just spiffy.
The only drawback to that mobo for me was it wouldn't clock past 175 on the front-side bus, so I picked up an NF7-s rev2 that runs at 12x200 for me with a lil 2400+ mobility barton. (35w)