How big is Gingerbread 2.3.5 on internal 8GB memory? How much space does the Gingerbread version 2.3.5 occupy on the internal memory drive ?
I've bought the Samsung Galaxy Player 5.0 and it promised  8GB, when I checked the size it said 5GB and only 4.85GB are actually available. What's going on ?
This seems pretty normal. The 8GB iPod Touch is similar - iOS takes a significant portion of its storage.

The device itself has 8GB of storage, but any OS takes space - particularly Samsung's flavor of Android, which has a lot of stuff added (Which, unfortunately, they don't want you to be able to remove).