The PCI card is made up of a LMC card on a PCI card adapater.
You can not however remove the LMC card from this card adapter and use it as a LMC card, the reason for this is the boot block versions are different and the bootblock version used relies on logic found on the PCI card adapter. This is maninly due to the very different bus speeds of the 2 form factors PCI Vs PCMCIA
You will see very bad RF and throughput performance and doing this is NOT supported.
The correct way of doing this is use a LMC cardwhich can be ordered with the part number AIR-LMC352
You are 100% correct for a PCI card but he needs to use a PCMCIA card for a laptop,
I also would not recommend using an antenna you buy on ebay as the FCC certification is for the system this includes the cable and antenna, if you change this then the install is responsible for the certification.
The certification is valid for any Cisco antenna that can be found at this link for the applications listed.