|The type of memory used on the video card has nothing to do with anything other than the video card. Which card? You may want to consider a card with GDDR5 instead.|
If you're installing a gaming card, make sure your power supply can handle the load. Gateway/eMachines doesn't have the greatest rep when it comes to power supplies. They use cheapo Bestec units which have a higher than average failure rate.
Best Graphics Cards For The Money: February 2011