Your internal soundcard will re-produce ... OK sound. Not much below the bottom level INTERFACEs, which is what we call music ADDAs. Something to watch out for is latency - the time between hitting a key on a midi controller and hearing the sound. This can be really long on a built-in card and disruptive. You can try, but most likely you'll need a USB interface.
Lots of people here use the Focusrite units w/ success. Many others bought Roland when they owned Cake and the natural thought was sonar should work. It usually did. Now Tascam owns Cake, and they have a new line that is very competitive. No one but Craig here has used them yet, but really no company should have much on any others. That goes for quality, too. If everyone is designing an interface at $150 there simply can't be much difference in the quality - same goes for $500. I can vouch for the $500 Tascam UH-7000, the older brother in the new line. Superb sound, which anyone can use if they have the monitors, although the 1st class preamps aren't much use to you. And it is a bit high on the latency. But Tascam has new drivers coming from in-house for the rest of the line, so maybe they are better. Perhaps it will defy gravity and trickle up to my unit. But it doesn't matter what you buy, so long as you can return it if you have problems w/ it. Since all interfaces work most of the time on different systems, it is likely if you have a problem it is some component combo in your computer that is reacting w/ one company's drivers. The next company's will most likely be fine.
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