Wireless question?

So, this might sound totally silly or even a little bit ridiculous to some of you, but I figured I’d just throw it out there and see what happens... basically, I'm looking at this Logitech wireless network card, the Linksys model, which hits 150Mbps on a PCI connection, and I'm just trying to wrap my head around the basics—is its whole purpose just to pick up the Wi-Fi signal?

Basically, yeah.

"Since the antenna detaches and comes with an extended cable, you can actually move it to wherever you get the strongest signal.">

I had a similar setup using a different brand's antenna with a 1.2m cable, and I guess I was pretty happy with how it performed.