I have an HP Pavilion Elite HPE-112y, and would like to upgrade in order to play current games at medium-high settings. The graphics card I have in mind is an AMD Radeon HD 7850, yet with that card being very strong and very new, I'm not sure if I need to upgrade my existing PSU (because I do not know if it can handle the card) or AMD Phenom II X4 925 Quad-Core processor. I would like to be able to play games such as GTA IV, Skyrim, Fallout 3 and New Vegas, and The Witcher 2 at High settings. If I need anything to be upgraded, could you point me towards an inexpensive yet effective upgrade? Thank you in advance.