Oreet!
First, right-click the attachment and choose "Scan with AVG" to check it for viruses.
I think it's a presentation file, which means you would need Microsoft Powerpoint to be loaded from the Office CD. As your Hard Drive space is limited and you'll probably never use Powerpoint, it's hardly worth loading it for just one attachment.
However, there is a small Powerpoint viewer, for those who don't have the full-blown program. Go to:
http://microsoft.com/downloads/details.aspx?FamilyId=D1649C22-B51F-4910-93FC-4CF2832D3342&displaylang=enand download the viewer. Then you should be able to open the attachment. If you've any probs, I'll call round and have a look later.
Edit: You'll have to copy and paste the link into the Internet Explorer address bar. (Why does this keep happening)?
Edit: Link is working now.