Don't see how it's possible to set it for half a line. It's one line, one and half, two, etc.

If you are wanting a block of text to have half a line space in between each line/row, then choose one and half spacing.

In Word 2003 you can have an icon for a choice of line spacing on the top toolbar. Rightclick on a blank part of Toolbar | Customise | and on the Command tab, choose 'Format' in the lefthand column and in the right column scroll down to line spacing icons and drag and drop the icon(s) you want up to the top toolbar.

This makes it easy to select what spacing you want for the whole document before you start, or change at beginning of a paragraph, or if editing and you want just parts of it then select the text and click on the icon.

It may be like it is in my Corel WordPerdect. Go to Format Line/Spacing I can change mine 1.0 mil at a time

Here is what you need.

http://office.microsoft.com/en-gb/word-help/adjust-the-line-spacing-between-text-or-paragraphs-HP010368776.aspx