only the engine sounds? i've encountered a problem about the ingame sounds some time ago. for my problem, it was about the sound drivers. you may try to install latest drivers.
To Kimi... "You were the Chosen One! It was said that you would destroy the Sith, not join them. It was you who would bring balance to the Force, not leave it in Darkness"
-----------------------------------------------------------------------
amd64 3200+ / msi diamond mainboard / 1024mb ddr400 / 128mb geforce 6600gt sli pci-e / samsung 160gb harddrive / asus dvd-rw double layer / asus cd-rw / coolermaster centurion 5 case / creative inspire 5.1 / microsoft wireless desktop set / lg 1780q tft