When you have pics that are bigger than the majority of surfers screen resolutions, how do you handle them?

Load them in a HTML page or load them directly in to the browser?

We have just purchased a ton of content with dimensions in the range of 3500px + on the longest side and im actually not sure how to display the content to the surfer, what do you folks feel would be the best way to handle larger images being used inside a paysite members area?

Regards,

Lee