Yes, as the others said, definately use a heatsink, and probably a fan too.
nForce2 got pretty hot, not as much as nForce 3 or 4, but still pretty hot.
I lapped my nForce2 back in the day, and put a Swiftech MCX159 on it.
Worked really really well, it overclocked like hell :)
Edit : Which...