For HD streaming WIFI is enough . Take a simultaneous dual band router if you have the budget which you have 7k . Use 5Ghz dedicated for streaming and 2.4 Ghz for other usage . The moment you use mix network than you are limited to the lowest like everyone selects b/g/n in their router . The moment any WIFI ' b' device connects then complete network is limited to 11 Mbit/s .
I have a HD player with a cheapo WIFI N 2.4 Ghz dongle and I am streaming from Belkin 600 HD router which has 2 usb ports . One usb ports has 2 TB with HD movies . I have streamed 22GB blueray iso and never faced any hiccups or stuttering .
Remember 5 Ghz has less range but can carry more data and 2.4 Ghz has longer range than 5 Ghz but will carry lesser data .
Even if you buy 2.4Ghz/5Ghz router select only N or A and dont select b/g/n or g/n or g/a . Each router has different interface and with people using dd-wrt its again changes so giving all examples .
For smooth HD streaming you require only 56-80 Mbit/s and N routers are 54 Mbit/s to 600 Mbit/s . Agreed the higher value is theoretical but with a good router you can easily do 80 Mbit/s .
Check out the WIKI
IEEE 802.11 - Wikipedia, the free encyclopedia . Than you also have different channels and channel width of 20 and 40 Mhz for selection so that minimum interference from your cordless landline telephone set or your neighbors WIFI .
Final conclusion use 5GHz and you will find in your complete society/colony no will be having 5Ghz . In mobiles S2 has dual band WIFI .
adding now that if you use WEP as security in WIFI than you will never get N speeds . Use WPA2 .