If you are afraid of a virus in powerpoints, don`t download them. If you don`t like powerpoints, just ignore them. If you do like them, download whatever you like.
When opened normally NO password will be asked. The password is just "modify protection" and will only come up when opened from within the program "Powerpoint".
For more powerpoints go to:
http://powerpointlog.blogspot.com
For EROTIC powerpoints go to:
http://adultpowerpointlog.blogspot.com
Check here if the file is virus-free:
http://www.virustotal.com/