Jpg versus png24

i’ve read that flash loves imported graphics in png24 format, but i see that there is usually a massife difference in size (jpg being much trimmer)

what’s the general concensus on this?

png gives you the ability to have an 8 bit alpha channel.
you can also change the compression settings in the publish settings or in the library to bring your file size down.

Macromedia’s Fireworks native format is png, so it seems normal, it’s integrated with their other softs.
Flash MX’s new feature of dynamically loading images works only with jpg though!?..