When the club goes through a color change or the picture on the front page changes, or we go through an upgrade I end up seeing a mix of new images and old stuff. I'm using Firefox 1.5.02 with the default settings for refreshing (it's set to automatic) and I know the solution is to refresh the page to see what is new.

My question is why the automatic setting doesn't give me the new stuff when the page loads? I create web pages for my employer so I'm curious to know what triggers this for browsers. Obviously the club pages have changed, but Firefox doesn't see that they have. Inquiring minds want to know why

Caching. Why download the same image every time (slow) when you can just store a copy on the hard drive (fast). And you can't just "look to see if anything has changed" because in order to compare the files, you'd have to download them.

So then the reason why the new graphics don't show up is because they are the same name as the old ones?

Yep.