Allways think of all the people not having fast internet access. There are users still accessing the internet with 56k modem.
With flash you have everything you need to make it modular.
Load a preoloader first, to show your visitor, that something is happening.
Load content, as it is needed (pictures only where you need them - and in the size they are displayed).
Allwas, if something is loaded, tell it to your visitors. Visitors with slow connections know, that they will see some status, or load information, before they can see content.
But this is the least they can expect.