Yep. Galaxy S(i9000) and it's variants(Captivate, Vibrant) have almost the same hardware. Just that Galaxy S(i9000) is slightly superior than it's variants.
But, their GPS... speechless.

Now, I know how to make the GPS on Galaxy S Captivate works already. But, it takes a plenty of time to LOCK ON. I would say around a few minutes for the 1st LOCK.
Then, the time needed for LOCK ON will be decreased overtime.