In my experience, the Realtek cards will use their own sound control program that needs to be used for volume. Perhaps the microphone port is muted or not set for 'mic boost.' If you're not getting any audio in, you'll need to check between sndvol32 and the realtek program (which could be accessed from your system tray, bottom right-hand corner where the clock normally is). Your laptop computer, likely has only 1 sound card that is integrated into the motherboard.
Microphones will need the mic boost if they're not processed before coming into the computer, otherwise would be VERY quiet.
