of the 2 connectors listed abouve, which do you think would get better reception?
The USB has a 2dBi antenna while the PCI card has a 5dBi antenna... so the PCI card is better in that regard. If you can move the PC around so that there is more or less a straight line of sight between the PCI card and your router then it probably would be better.
But if you have a situation like I posted above, then the USB adapter might be the way to go. Altough it's antenna sensitivity is lower, you can move it around easily.
At the time I worked on my friend's PC, I considered the USB adapter. But it was more expensive than the PCI adapter and 15dBi antenna combined.
Another thing to consider... is your USB 1.1 (12Mbps) or USB 2.0 (480Mbps)? You don't want to buy the 54Mbps USB adapter unless your PC has USB 2.0.