Dell Inspiron 1420 (Mid 2007) - Manual (Page 147)

Adding and Replacing Parts
147
Replacing a WLAN Card
NOTICE:
The connectors are keyed to ensure correct insertion. If you feel
resistance, check the connectors on the card and on the system board, and realign
the card.
NOTICE:
To avoid damage to the WLAN card, never place cables under the card.
1 Insert the
WLAN card connector into the system board connector labeled
"WLAN" at a 45-degree angle by aligning the notch on the WLAN card to
the slot on the system board connector.
2 Press down the other end of the WLAN card and tighten the screw
securing the card to the system board.