Many users have reported that the number of spaces between lines of text is 'all messed up' after they began using Word 2007/2010. Many 'blame' Pathagoras. While we typically assume full responsibility for anything even remotely associated with the use of Pathagoras, this is not our doing.
This is simply a function of the stupid way that Microsoft changed all of your 'normal' settings without telling you or asking your permission. (Pardon the venting -- this is the only page where I do so.)
Luckily, the fix is easy. Do this.
Open any document. Right click anywhere on the page. From the right-click menu select 'Paragraph.' Select "0" for spacing before and after, and select Line spacing 'Single'. Then, at the bottom of that screen, click the "Default" button and choose to apply the changes to the Normal template.
That should cure it.