If your using Vista, then NO, no real difference in either codex wise. if you are using XP, then yes, you can gain a few nice features via the SB. I do the same thing you do, but also do Pro Audio sound stuff, so I need a bit more. Heh, I use an $800 mic to talk in vent via an m-audio breakout box for VENT.
In anyways, you will find a tad bit better sound quality to your ears, in either operating system via Sound blaster. But, if you are not an audiophile, then don't worry about it. You will probably use a USB mic and headset in anyways. Both sound blaster and the onboard sound provide great surround sound.