actually MAC - do this if you would

<img src="http://www.freewebs.com/qbasicjedi/Qbasiclogo4.png">
paste this into notepad, save as "image.html" with quotes and load the html. it will load his logo without any plugins.
or... even install windows 95 with ANY browser past ie 2 or 3 (then load yahoo.com and see how bad it looks in ie3) and view it.
it will work fine. minimum requirements for viewing a png file: a 386 with DOS and arachne. ALL major browsers and 95% of weird obscure browsers support png. the dll required to process them in internet explorer is in the windows system directory before you ever go online with a new machine. and btw pete - you should know better.