Select the whole table (right mouse button pick from list to be sure)
Move your mouse over the corner of the existing table that you want to line up with
You should see a four way pointer, right mouse button and select from the bottom of the list 'Move Special'
The pop up box will display the current location of that corner, make a note 
Plonk the new table down somewhere, then select the whole table
Move over the corner of the new table that needs to line up with the previously mentioned corner
Type in the values that you noted down earlier
Voila!