If I have my facts straight, there are basically 4 combinations of nForce2 chipset, because there are 2 versions each of south and north bridges.
South bridge can can have IGP or not. (I'd just as soon get without, since the integrated MX graphics won't cut it for me.)
North bridge can have "SoundStorm" APU or not. (Both versions have on-board sound. It's just a matter of whether the chipset has the APU for processing it, or if your CPU has to eat cycles doing the work. The full SoundStorm APU is as good or better than most sound cards on the market, supposedly.)