Please give me some advice for a project

I’m going to create a website to show some product pictures to the customers.
Each of the webpage page will show about 20 thumbnails of product picture.
I would like to have some animation & sound effect on the thumbnails, so I’m going to using Flash to do the job.
I am wondering, should have a page load 20 small thumbnail swfs, or make a big swf to load 20 thumbnails.

The first option is easier for me, but I’m concern that loading 20 small swfs might use too many computer resources.
I don’t want to slow down or crash my customer’s browser.
Any suggestion?