If you have Microsoft Word 2003 try this option.
Go into the document
Click on View
Click on toolbars (if toolbars is not not showing, click on the down arrow to bring up the other options and then click on toolbars)
Make sure that the drawing toolbar is checked
Now back on the document, go to the place where you want to start the line.
At the bottom of your screen (or top, depending upon where this toolbar is displayed on your screen) locate the icon on the toolbar that is diagonal.
Click on that icon
Starting on the document at the place where you want to have the line, Click on the Right mouse button and while holding this down, Press your SHIFT key on the keyboard. IMPORTANT! Hold down both the mouse button and the SHIFT key.
Drag the mouse from left to right for the amount of space you want this line to appear on the document (by pressing the shift key, it keeps the line straight). Drag the mouse to the end of the length of the line.
Now if the line is not in the place you want it on the document, then take your mouse over to the line, and some arrows should appear. Click on the line and drag the line to where you want it on the document.
I hope this helps!