Quite by chance, I found a program that'll change jpeg or most any other to png, or vice versa for
DTG like cafepress, zazzle etc. "Image Converter Plus" does this in 10 sec. without going thru layering. The best part is it cost me $50. You can also change image resolution for e-mail, blogs, e-mail signatures, etc. I'm glad I never bought photoshop for these applications. Hope it works for your applications!
Graphics design program for changing formats: 
