graphic file format, which?

Which graphic file format is most likely to be readable on any modern operating system--.tif, .jpg, .bmp, what? (I don't want to save and email a raw file.) If .tif, then what flavor? (My scanner program, which I have to run out of Windows, since I can't get the scanner to work right in Linux, has got some formats that I never even heard of!) Oh, the scanner is fussy in Windows XP, also. Some of the programs it should work with, it won't. --doug