I need to update my graphics card, which is an ATI Radeon HD 4850 series, but when I searched for an update, a popup said "We were unable to find a driver for your system. Your operating system may not be supported." Any ideas on how I can fix this? I use this computer for gaming, World of Warcraft to be specific, and sometimes, my computer would just shut off by itself without a warning when entering into a high graphics place.
Operating System: Windows Vista 64-bit
Processor: Intel(R) Core(TM) i7 CPU
Graphics: ATI Radeon HD 4850 Series