Go here, download and save the full 57.5 mb SP3 update for Office to your drive. (OfficeXpSp3-kb832671-fullfile-enu.exe)

http:// www.microsoft.com/downloads/ details.aspx?FamilyId= 85AF7BFD-6F69-4289-8BD1 -EB966BCDFB5E&displaylang =en#filelist

take the spaces out of this link before copying and paste into your browser address window. I can't post the link without the spaces.
or you may want to delete and re-install microsoft office from the disk

After the download is complete, double click to install. If you're lucky, you won't be prompted for a cd and it should take care of your problem.