I have an Alieware Aurora R2, WAS using a NVIDIA GeForce GTX 460 graphics card. Sadly my graphics card got corrupted and is out of commission. What would be a good upgrade to play games such as World of Warcraft and Diablo? As far as a budget, I would say around $300. I'm not very computer savvy, so if you need to know more, please ask. Thanks for your time.