USB 2 is a newer revision of the USB standard. Where USB 1 (built into the Lombard) will transfer data at 11mbps USB 2 transfers data at 480mbps. It requires the processor to do more work than FireWire, but it's still loads faster than the built-in USB controller.
PC Cards are add-on cards for laptops and desktops that have PC Card slots. They used to be called PCMCIA cards/slots. On the Lombard there is one PC Card slot on the left side of the unit. The card I have fits in that slot and has a plastic module on the end of the card with two USB 2 sockets.