For images on websites, jpg/jpeg will usually provide images in much smaller file size than .png, something to consider for any dialup users visiting your site and consumption of your monthly bandwidth allowance from your web hosting service.
which willlower down the quality and i hate dialup users
Actually, png files are bigger than they need to be. You can adjust the jpg quality with most graphics programs so that you cannot notice any distortion whatsoever. I use internet with high bandwidth, and I hate it when webpages and flashpages take more than about 15 seconds to load. If I haven't been to the site before, I will usually just close it immediately. You might want to take that into consideration before you publish large png graphics onto your large capacity flash website.
You may even want to consider a splash page giving the user the option of an html or flash site. Or maybe just a preview of the flash site so they know to stick around.
god none of u know ANYTHING ABOUT QUALITY! Angry
For some reason, I seriously doubt that you yourself know very little about quality. Especially with how angry you get when people try to give any advice.