The card may be doing some processing. Depending on the exact model of the card it may use the cpu as well. Is it a PCI-E one? I have read of this being an issue with PCI-e cards. I have a PCI-E sound card, but never used a mic on it, line seems to work fast.
Windows 7 also has an ability to playback a device(under recording-> listen to this device.), with that option there is a slight lag, but not 2 seconds. This is done in software and not recommended for most use
In the digital world, the card takes the analog sound converts it to digital, does its thing, then converts it to analog for playback(on the card or speakers depending on your setup.)
Depending on the card setup, it may be able to just pass analog along, but not always. For instance, I use line-in, the cmss features also happen to the audio from line-in(so there is some processing, but it does not seem to include any noticeable delay).