I installed the hotfix mentioned there, and all my synching issues are fixed. The game runs absolutely perfectly now.
If you have a multi-core processor, and just cannot seem to get this problem solved, give this hotfix a try. It's not public yet, so you'll have to give Microsoft a call to get the hotfix for free. (Or google for it, but uh, you didn't hear that from me.)
NOTE: This solution is only for people with a multi-core processor!
For AMD dual-core users, there is a official AMD fix at [URL=http://www.amd.com/us-en/assets/content_type/utilities/AMD_Dual-Core_Optimizer_113.zip]. It solved the problem for me instantly. All the other solutions failed. I hope it helps others too.
i was having the same sync issues with my Phenom II x4(quad core) xp-32bit machine and found the 'amd dual core optimizer' didn't make much if any difference.
i 'did' find however running BGE in various compatibility modes had some different results, the best being 'Windows 98/ME'. made most cut scenes sync with audio (did notice one or two tho) as well as general play seemed more fluid.