On my PC, if I right click on an image file, Picture Manager (PM) is under the "Open With" part of the list that appears. PM has an "Edit Pictures" button which leads to, among other things, Crop and Resize - both useful for posting on this forum. Resize reduces both the size (pixels) and the file size of an image.
Picture Manager seems to come with all versions of Office, up to 2010. This link
http://office.microsoft.com/en-au/help/about-picture-manager-HP001001721.aspx give 2 options to start PM to fix pictures.
When you installed Office, was there an option to install PM? You should be able to add it by inserting the Office CD and selecting modify. Note - I'm assuming this will work, it works for other programs - perhaps someone can confirm or deny that this will work.
Good luck,
Jim