Re: PC hardware upgrade help.
Your computer just needs a new graphics card, it doesn't need any more RAM than 8GB for games really. I have 4GB and mine runs the D3 beta perfectly. I have a Nvidia GTX260 which runs it on high settings so you should be great if you just buy a GTX560. Reading the specs on the 560 on Nvidias website it says that the minimum PSU should be 450W and your HP has a 460W power supply so you're cutting it tight on power. If you have the cash, go out and get another power supply, a 550W I'd recommend. Also, make sure that you have 2 6-pin PCI-E power connectors to power the GPU!