You could always go usb. Some of the newer ones allow you to move the antenna around for getting a better signal, and its much easier to use with multiple pc's.
Not particularly, I've ordered one for my new build, comes tomorrow, can tell you then, but I suppose there are far more in depth reviews than I can give out there on the internet.
One thing to look at is if your router has a 5ghz signal. If it does you want to get a card that supports it to take advantage of it. I didn't look before I got my card and got screwed.