$850 build for general computing, light media work

Solution
I don't know of any micro-ATX LGA 1150 motherboards with integrated WIFI. You could just pick up a PCI-E wireless network card. This one isn't really cheap, but it's dual band and should work well.

Rosewill N900PCE Dual Band Wireless N900 PCI Express Adapter, IEEE 802.11a/b/g/n 2.4GHz 450Mbps/5GHz 450Mbps, 64/128 bit WEP, WPA/WPA2 $32.99

If you step up to a full-size ATX motherboard and case there are a few options with built-in WIFI, but they aren't cheap. The cheapest one is about $200.

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007627%20600438202%20600009016%20600326189%20600053401&IsNodeId=1&bop=And&Order=PRICE&PageSize=100
It looks like a good general computing system, but there are a couple improvements that can be made. That Sandy Bridge CPU is two generations old now. You might as well go with the current LGA 1150 socket and a Haswell CPU. Here's a combo for a Haswell i3 and the RAM you picked out:

http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.1524904 $194.98 (Intel Core i3-4130 Haswell 3.4GHz + G.SKILL Ripjaws X Series 8GB

The CPU change will require a new LGA 1150 motherboard. This one is about the same price as the one you picked. ASUS H81M-A LGA 1150

Yes, 600W is overkill for this type of system. You can use the modular 430W version to save some money.

CORSAIR CX430M
 
I don't know of any micro-ATX LGA 1150 motherboards with integrated WIFI. You could just pick up a PCI-E wireless network card. This one isn't really cheap, but it's dual band and should work well.

Rosewill N900PCE Dual Band Wireless N900 PCI Express Adapter, IEEE 802.11a/b/g/n 2.4GHz 450Mbps/5GHz 450Mbps, 64/128 bit WEP, WPA/WPA2 $32.99

If you step up to a full-size ATX motherboard and case there are a few options with built-in WIFI, but they aren't cheap. The cheapest one is about $200.

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007627%20600438202%20600009016%20600326189%20600053401&IsNodeId=1&bop=And&Order=PRICE&PageSize=100
 
Solution