Last year i purchased an Acer Aspire 5553G laptop and i've been wondering ever since if it's graphics are upgradable. The laptop has two chips and enables you to switch between them both. They are; an ATI Mobility Radeon HD 5470 and an ATI Mobility Radeon HD 4250 (which i believe is integrated into the motherboard but I am not completely sure). I have read many posts online, some agreeing, some disagreeing. So naturally I am unsure as to which side is correct. Any help would be greatly appreciated.

Many Thanks,