The video card will need to be bumped up to be able to play WoW on medium. You would actually see better performance off the integrated GPU than you would that HD5450. Might I suggest the Radeon HD6670 or Radeon HD6770. The HD6670 would get you playing smoothly on medium settings where as the HD6770 would be pretty smooth on high settings. Both of the cards will needs shadows off and AA turned down low for raiding though if you want to keep the framerates smooth as possible.