Is a sound card worth the money?

First off i will say i know basic NOTHING about what makes good or bad sound from a sound card of any sort. So i wish to ask people who have had to use standard on-board mobo sound then switched to a dedicated sound card. 

How much difference does it make? 

Is there much difference between low to high end cards?

If i am just using mid-range gaming headphones and mid-range earphones (nothing too flashy but good quality for i use them for) would it even be worth the money? 

Any input would be really helpful because as said...i know nothing on this subject. 

money always makes the audio sound better.

most newer mobos have fairly decent sound on board (use the rear hookups)

for the best sound use a DAC/amp with headphones