If you use safari for Mac or PC, ore any other browser showing the downloading process (including names and files size).
In Safari under the windows menu, it's called 'Activity'.
Maybe under FF, firebug module could help, I don't really know.
Mac OS X Tiger Or Leopard - VMWare fusion 2.05
From my experience TW will load the loading (wait) image, skin graphics, mp3 associated with the default movie, map and the first scene. While viewing the first scene all the subsequent scenes load in the background. Whether you have 50 panos or 2 the first scene should appear with the same wait time. It is not a big deal but sometimes users will chose a scene that has not been pre-loaded yet so they will have to wait a few moments. Other than that the user should have a pretty good experience. Also, if it matters, mp3 files for scenes do not preload. They load when the scene loads and sometimes if you have a slowish connection to the Internet the mp3 may pause a couple of times while playing. This is why I like to use mp3 bitrates of 64 to 96 but never 128 or more.