I am buying a Dell XPS 8700 desktop that comes with the N-1704 N, single-band (2.4 Ghz) wireless card. I am thinking about replacing the stock card with an 802.11 AC dual band card, preferably with an external antenna(s) that I can move around to get the best signal. I don't want a USB adapter, but rather a built-in one. Has anyone done this? What are my options? I am confused by the sizes and formats for wireless cards as they would pertain to a Dell XPS desktop. My current router is a dual-band (2.4/5.0Ghz) Asus RTN-66U router that seems to work well. Would going to a dual-band AC wireless card help me now, or only if I get an AC router?