Vista - Can't open pps file attachments

I have got some e-mails from friends with pps files attached, when I try to open, a Windows Photo Live Gallery window pop-up and it says:
Photo Gallery can't open this photo or video. This file format is not supported, or you don't have the lastest updates to Poto Gallery.

I already downloaded and installed PowerPoint Viewer 2007 and nothing...

I changed the following:
For .PPS files (Microsoft PowerPoint Slideshow)
* Click Start, type regedit.exe and press ENTER
* Navigate to the following branch:
HKEY_CLASSES_ROOT\PowerPointViewer.SlideShow.11\shell\Show
* Right-click Show and click Rename
* Type the word Open so that Show is replaced by Open command
* If you have PowerPoint Viewer 2007 installed, repeat the above steps in this key, as well:
HKEY_CLASSES_ROOT\PowerPointViewer.SlideShow.12\shell\Show
* After changing Show to Open, close Registry Editor window.
but still doing the same...

CAN SOMEBODY HELP ME?
PLEASE....

A quick work around is to "save" the .pps attachment to your desktop. The way you have your power point viewer setup, you can then double click the attachment on your desktop and it will open it for you.