The mic/line is probably the correct input and it will auto-detect which ( mic or line input ) is being used. Different OS (7 or 8) and the driver you installed likely gave you different choices. You should also have a properties choice that will show you relative "levels" and perhaps the mic is on but the level is turned down. With my external Sennheiser mic I have, I have to use the +20 db option to get reasonable input. I tried looking up your manual, but Dell requires info from your laptop to download. You may need to look up the mic input levels in the manual if you can't find it.