If you do have PowerPoint installed, there may be a problem with the file association. You could try to download the pps file to your computer and open it that way, or you could try to fix the file association yourself. Start by opening Windows Explorer (the program that shows your files on your hard drive) and go to Tools-Folder Options. From there, click on the third tab that says File Types. Scroll down the list to see if pps is there. If it is, highlight it and click on Change. Then find PowerPoint in the list that pops up and then click OK to save it. If pps isn't in the list, click on New, type in pps in the box that pops up, click Advanced, and look for Microsoft PowerPoint Slide Show in the drop down list. Click OK, then Close, and you should be set.