PPS attachment won't open without downloading

Hello, Recently had to reformat HD with Dell's help. Forgot to ask them how to automatically have PPS file attachments open in Outlook Express 6. I can download and open w/o a problem but hate spending the extra time. What did I NOT do this time that was done before?
I read one of the suggestions Untick "Do not allow an attachement to be saved or opened that could potentially be a virus" that was supposed to be under the Tools/Options tabe, but I don't have that on my version.
Thanks to you kind people...