Open word 2000 as normal, add your table,highlight the cells you want to hide, go to Border Control (Square box on right side of tool bar)click the arrow for options and select the bottom row, 2nd left.
Your are mixing up two things. Gridlines shows the placing of the table and the cell edges when you don't want the the borders of the cells printed. It is easier then to input your data. What you want is Format - Borders and Shading and on borders click in the none box. Before you start make sure your cursor is within the table.