Basically they need a web browser and access to the WebHelp. Preferably Internet Explorer or Firefox and whatever the browser, recent versions of each. And if you have any Flash content in your help (such as Captivate movies) the browser needs a recent version of the Flash Plug In or Helper object.
I believe Google Chrome is not a supported browser and you might see issues with other browsers than IE or FF.
Helpful and Handy Links
Thank you for the info.