import arcpy Fail!

I'm a python beginner. When I try to import arcpy in pythonwin I get this:

>>> import arcpy
Traceback (most recent call last):
File "<interactive input>", line 1, in <module>
ImportError: No module named arcpy
>>>

I run a 64bit machine with and use ArcGIS 10.0 and Python 2.7.

Thanks in advance.