My mantra is always: "Wire if you can
. Wifi if you must
I'd go hardwired on my main desktop if at all possible. Especially if you do any serious downloading or streaming. You'll be a lot happier if you do. Count on it!
For add-in wired NICs, I'll usually opt for one of the better Intel or Netgear GB models. That or preferably a used "server grade" NIC card if I have a spare or "scrapped" one sitting around doing nothing on my junk parts shelf.
Can't help you with a desktop wireless card. Never bought one. I've only used USB dongles for that so I could swap them out more easily, and also to reposition them for better reception if needed.
On a related subject: Does anybody have any personal experience with the most recent generation of hub-adapters that use your wall's power lines? I've heard mostly good things about them. About the only knock on them i've heard was their relative high cost compared to other alternative.
Anybody have one of the newer models?