Download the appropriate file for your operating system :

(Note - Please make sure you have the latest updates for your operating system)

WINDOWS:

WindOws XP - DOwnload

Windows vista- DOwnload

Mac os:

Intel - Download

Powerpc - Download

ALL Other Operating Systems - http://www.adobe.com/products/acrobat/readstep2.html

What operating system am i running?

if you can see this (may have black background) on your screen you are running windows vista

If you can see this on your screen you are running windows xp

If you are running mac os x you should be able to see an apple in the top left hand corner of your screen. to find out whether you are using an intel proccesor or a Powerpc one, click on the apple and then select 'about this mac' from the drop down menu. a dialog box like this should pop up:

if it says g5, g4, or g3 instead of intel in the circled area, it is a powerpc.