The IBM's can accept other mini-pci cards from other manufacturers, but you will need to remove the card and the driver before installing the new one. The new driver installation procedure is different for different operating systems.
About your "lock", here is a link to your units Hardware Maintenance Manual - the information should be in there...
http://www-307.ibm.com/pc/support/si...cid=MIGR-53683
Information about how to change the mini-pci card is in there too.