The powersupply is crap, and you probably want a PCIe WLAN card if you intend to use it over WLAN.
Get this
XFX Core Pro 650W to use as your PSU.
And then I would recommend this
TP-LINK TL-WDN4800 Dual Band Wireless N900 for use as a WIFI card.
Also an aftermarket CPU cooler would be good. Xigmatek Gaia or Cooler Master Hyper 212 EVO would be a reasonably priced investment.