No. It's the memory bus width. That and the video card's memory type and the speed of that memory determine how fast the GPU communicates with the memory.
Before you buy anything, could you post your Presario's model number? Apparently, it's not as old as I thought, and you might be able to upgrade it to something a lot more powerful (able to play modern games) for not a lot of money. AMD CPUs are cheap.
"They should rename the team to the Washington Government Sucks. Put Obama on the helmet. Line the entire walls of the stadium with the actual text of the ACA.
Fix their home team score on the board to the debt clock, they can win every game 17,000,000,000,000 to 24. Losing team gets taxed by the IRS 100%, then droned."