Kobus: The SIM slot is in all these laptops, whether they have the modem or not - it's not part of the add-in modem card. See here
- the SIM contacts are part of the interface to the card, which enables laptop makers to put the slot anywhere on the laptop regardless of where they put the modem.
As for the card not showing up in Device Manager - this may or may not be a problem. Unless your laptop got the modem as an "aftermarket upgrade", you should have a sticker on the bottom side regarding the modem (regulatory compliance, IMEI, etc...). If it's not there and then your laptop likely doesn't have a 3G modem.