Attachments cannot be opened/downloaded

My brother overseas sends me by email a lot of jokes in attachments and I cannot open/download the vast majority of them. I always scan any attachment that comes from a trusted source. (Actually I scan EVERYTHING by AVG and SUPERantispyware after downloading, yep even after downloading software from MG)

Some examples: video/x-ms.asf and "pps"

With which (free) software can I open/download these files?

Thank you.

 

pps is a PowerPoint slide show. You can download a free PowerPoint Viewer.

For video/x-ms.asf, this might be a solution: video/x-ms-asf-plugin for firefox

 

Thank you usafveteran. The PowerPoint Viewer works perfectly! :yum

I looked up the link for the Firefox extension but couldn't find any download or suggestion where I could download it. As it turned out, I had Firefox's NoScript partially on in the email for all this time. Allowed it fully and was able to download it and view it in Irfanview.