Hi Cathyn. I replied to your post at our site.
It was a default upload type issue that has to do with us using the Multi-User WordPress (based on WordPress but has some differences).
It has now been opened to allow Powerpoint, Excel, and Word files to be uploaded. (In case anyone running MU needs to fix this, just add: ppt doc xls to the SiteAdmin-Options-Upload File Types box.)
Also, back on track to regular WordPress. I also installed the ThinkFree Viewer Plugin which allows people without Office to view these three Office document types. It is designed for WordPress. But, so far, it seems to work on Mu (multi-user) as well as regular WordPress.
I blogged the process to use and see a demo of this plugin here:
https://simplenames.com/blog/2007/09/21/view-office-documents-in-your-blog-word-excel-and-powerpoint/
Since it turns out this topic is related to our specific type of WordPress installation, please address further questions on this upload issue on our blog or through email.
Thanks.