I got the game a few days ago and I am having the same problem I had with Spore where the sound would not always work. It seems complete random the sound works fine during the opening stuff but once it gets to the main menu it stops working. I fixed it in spore by changing its sound settings to use 4 speakers when my laptop only has 2 but there is no option for that in Sins so all I can do is restart the game and hope it works.
Laptop Specs
Toshbia Satalight Pro A200 PASE7
Vista Business 32-bit, up to date unless the icon is being stupid and not showing
Sound card just says “Realtek High Definition Audio” and another saying “High Definition Audio Device” Drivers are up to date going by the Toshiba site.
Game version is 1.09b (i think that is what it said when I installed it had the beta box checked in the settigns)
edit: er did i post this in the correct section i dont see it showing up and it dose not say Technical in catagroy on the my posts thing)