Yes on both accounts.
Sound recordings will be night and day over an onboard solution. The quality of the ad converters are far superior, a motherboards line or mic in was never designed with quality recording in mind, they're at best meant to handle a passable mic input for gaming / web phone calls.
Output depends on what you are listening through. With a decent set of monitors and an amp accepting balanced +4db input the sound quality of playback will also be far higher. Through a set of pc speakers or using the digital out you probably won't notice. You also need to be aware that whatever you listen back on, the 1212m use 2 full size balanced jack outputs not just a stereo mini jack.
And performance wise the emu card has an onboard dsp and effect set which can be used from within your music software as plugins and offer no cpu hit. They aren't on a par with the best 3rd party plugins but then those aren't essential on every track.