[shanedanger]

I think the difference in this case is around 40kb, haha.

[chaosmachine]

Well, the main difference is you won't end up with blurry text and artifacts.

http://imgur.com/GkCbP.png

[shanedanger]

holy smokes, chaosmachine, you just changed my world! (not being snarky either, I seriously never knew that in all my days of amateur photodoodling)

[Scriptor]

A very general rule I learned is that png's are best for images with large areas of the same color (screenshots, logos, text) while jpegs are best for images with lots of color variation (real-life pictures, for example).

[kpreid]

PNGs are good at compressing gradients too, I hear.