Can i play WoW, GW, PWI, RIFT and other MMORPG's with a integrated ATI HD4200 Radeon?

No man. Not RIFT. WoW on low. It's the weakest graphics solution on the market. What you'd want to do is grab a cheaper computer at your local big box store and throw in a 6570/5670 GPU for about 50 pounds.