I never actually used a PNG, but I just ran a test, wow, a 1536 x 1536 test file was 600k as a high quality JPEG, 300K as a low, PNG was about 220, and quality was much better than even the high quality JPEG, none of those pesty artifacts. What is the downside? Poser 4 on the Mac can use PNGs, have all versions of 4 been able to use them? Is is going to bother people not being able to open (and edit) the PNGs on paint programs that don't support them?