You won't be able to run the game with Windows XP. All the new Need For Speed games, including Most Wanted 2012 use the Frostbite engine which is DirectX 10 and 11 only. Windows XP only supports up to DirectX 9. You're going to need to upgrade to Windows Vista, 7, or 8 in order to play, and your Radeon HD 5450 probably won't handle the game well, if at all.