How to use UNPIVOT in Sql Server : I have a table 'StoreDetails' with the following data.

    -------------------------------
     Store	1		2		3
    -------------------------------
    101		138		282		220
    102		96		212		123
    105		37		78		60
    109		59		97		87
    -------------------------------
My required Output is..

    ---------------------------------
    Store		Week		xCount
    ---------------------------------
    101			1			138
    102			1			96
    105			1			37
    109			1			59
    101			2			282
    102			2			212
    105			2			78
    109			2			97
    101			3			220
    102			3			123
    105			3			60
    109			3			87
    ---------------------------------
How can i get this result set using UNPIVOT ?