How to detect if Acrobat, Flash or Video drivers are installed

How to detect if Acrobat, Flash or Video/Audio drivers are installed

If the programs or drivers are not installed,
the corresponding page will be shown
Adobe Acrobat	`missing_acrobat.htm` or `missing_acrobat.html`
Shockwave Flash	`missing_flash.htm` or `missing_flash.html`
Video/Audio driver (codec)	`missing_mpeg.htm` or `missing_mpeg.html`

The page should display a message telling the user that the drivers must be installed before running the publication.

Of course, if the publication is on a CD-ROM you can include directly a link to the installer for Flash, Acrobat or the Video Codec.

If no page was provided, a short message, telling the user that he needs to install either Acrobat, Flash or a Video or Audio driver will be shown to the user.