You should get a r9 280x. This gigabyte r9 280x is clocked at a 1100mhz boost clock. So it's one of the fastest at $300.00. http://www.newegg.com/Product/Product.aspx?Item=N82E16814125490
Everything's good although you may want to go with a r9 280x. It beats the 770. Here's one http://www.amazon.com/gp/product/B00FONITA6/ref=s9_simh_gw_p147_d2_i2?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0HRT4JKPQCHKFQS5XDCM&pf_rd_t=101&pf_rd_p=1630083462&pf_rd_i=507846
Your psu is fine. 2133 ram makes minimal difference. A 270x might be better than the 7870 though. Here's one http://www.amazon.com/Gigabyte-GDDR5-2GB-2xDVI-Graphics-GV-R927XOC-2GD/dp/B00FONITCE/ref=sr_1_1?ie=UTF8&qid=1384227112&sr=8-1&keywords=270x
r9 290 or 280x will give you the best for your money. Here's some http://www.newegg.com/Product/Product.aspx?Item=N82E16814125475 and http://www.newegg.com/Product/Product.aspx?Item=N82E16814125479
780ti is better. Here's one http://www.amazon.com/EVGA-Superclocked-Dual-Link-Graphics-03G-P4-2883-KR/dp/B00GFZMI3G/ref=sr_1_1?ie=UTF8&qid=1384206303&sr=8-1&keywords=780+ti
The wifi card would be much better. They get much better connections. Here's one http://www.amazon.com/Intel-6235AN-HMWWB-Centrino-Advanced-N-Bluetooth/dp/B007QXLIWI/ref=sr_1_1?ie=UTF8&qid=1383610411&sr=8-1&keywords=intel+wifi+card
Here's one http://www.amazon.com/Belkin-F7D2102-Micro-Wireless-Adapter/dp/B004N625B4/ref=sr_1_1?ie=UTF8&qid=1383510376&sr=8-1&keywords=belkin+wireless+usb+adapter