http://www.youtube.com/watch?v=7AzxbIahhGk&feature=related
ones that currently walk skyrim are MIDGETS
The footage isn't from a pre-release version of Skyrim or anything, just regular Skyrim. Giants were always as big as you see them in regular Skyrim. Any other size is either done by a mod or by console commands.
or do they get bigger later on ? im still a newb in skyrim
They stay as they are. I'm fine with their size. They're big enough. And they deal enough melee damage to be very scary, especially at lower levels.