The solution

WinHelp supports wrapable or "autosized" tables.

Unlike left and right aligned tables, centered tables wrap text automatically inside the table cell when the Help window is resized.

Centered tables are created by selecting the table and changing the Cell Height and Width attribute in Microsoft Word to Centered.

The only disadvantage: the narrow table cells created cause your topics to look odd, but I believe this shortcoming is definitely worth it. Take a look at the examples provided.

Table with one column wrapping