Click Start - Run, type
ClearType and then select
Adjust ClearType Text. In the dialog that appears make sure ClearType checkbox is ticked and then go through the remaining dialogs to complete the wizard.
Note: you need to complete the entire wizard otherwise the settings will not be saved.
For screenshots and step by step instructions see http://www.howtogeek.com/howto/28790/tweak-cleartype-in-windows-7/
As the page suggests some applications might be doing their own font smoothing so in that case the steps above might not be sufficient.
Also you seem to be using OpenOffice which is an outdated branch and probably not supported as well as LibreOffice. If the problem is not solved through ClearType Settings then I would strongly suggest to switch to LibreOffice instead as this is probably better maintained and is the 'established' way to go.
And, optionally, if you really want to know the reason why LibreOffice should be used over OpenOffice have a look at http://www.linuxinsider.com/story/76331.html.