Files in Microsoft Word or Excel generally present no problems when it comes to extracting the text into a Translation Memory.
It is, however, important to ask if a MS Office file contains image files which feature text. If an image such as a diagram is integrated into the document as an image file (a jpeg, for example) that means that any text it contains will not be editable. The whole image would thus have to be reworked from scratch. For this reason, it is better to integrate images on their own, and then put in the text as normal.