I recently updated my G60-507DX to Windows 8 as well. The sound worked UNTIL took the memory to 4GB. The machine came with 2. I took it to 3 with no issue then to 4 and boom sound stopped working. If you take the memory back down to 3 or run msconfig and limit the memory to 4096 (which really ends up being 3GB really) then the sound works fine and the sound even works with Microsoft's sound driver even if you uninstall the Conexant Pebble one... I suspect the problem existed even with 7 but I didn't upgrade the memory until I had moved to 8.
I hope this helps someone else.
Ted