If you want native SATA your options are the KT600, KT880 and nForce2 Ultra 400Gb chipsets.
Overclocking: only the nForce2 has a PCI/AGP lock.
Audio: the best one is the SOYO KT600 Platinum, which uses a PCI CMI8738 6-Channel chip, instead of integrated AC97. Much better quality.
VIA KT880...