I was wondering if anyone has any strategies for optimizing the pre-loading of images via javascript?

I'm porting a Flash application into html/css, attempting to recreate the UI as close to the original site as possible. It's essentially a photo browser application, where a high-res image is shown when the user hovers over a link. There's about 50-80 of these images per page.

Pre-loading all the images individually creates a load time significantly longer than that of the Flash application. The amount of data is the same, but I have to assume the longer load time is due to the number of round trips that have to be made to the server for each image.

Also, I'm looking at a significant load time for each page even after the images have been cached, because the page still needs to contact the server for each image to receive the 304 Not Modified code.

Does anyone have any suggestions for speeding this up? Would it make sense to possibly try creating one huge image sprite that gets downloaded in a single request rather than 50-80 smaller images that each take a single request? The goal here is achieve a similar load time to the Flash site.

Thanks. I know this doesn't sound like an ideal way to do things.