No I don't agree with baisaz. I have a Soundblaster Live 5.1 on my system with some good Altec Lansing speakers and it is lightyears above the sound quality of the built in sound.
Further, the Audigy models supported use the same chip or a closely related chip (from one generation after) as the Soundblaster Live.
I have a later generation Audigy than those, and while it might have higher specs, I can't use it.
So far, I've heard negative statements from Davey, in favor of the nearly unobtainable Envy 24 based cards and I've heard negative comments from baisaz favoring Audigys.

But, honestly, in my own experience, to directly answer the question you answered, yes install your SB card. You'll notice the difference.