Lets get up to date MYOB/Atlas and not lag behind the 8-ball as Microsoft IE did until several years ago.
Web page graphics and aesthetic page appeal require attractive graphics (other than the poor quality .jpg and .gif) with a transparent alpha channel.
The alpha (transparent) channel of .png graphics has not rendered the graphic properly on either Safari 5.x or Firefox 4.x where the alpha channel is simply filled with the colour black. Needless to say, this looks very poor.
Internet Explorer (several years and versions ago) was infamous for its lack of .png support by rendering the alpha as a grey box.
Interestingly, .png graphics were developed out of the necessity for a high quality, lossless and licence-free (unlike .gif), image format designed explicitly for internet usage; hence the anagram .png (Portable Network Graphics)