Here's a comparison chart for Q8/2008 from Tom's Hardware. Scroll down and click on the game and settings you are interested in and it will rate the various cards in order by framerate. You'll find a single HD 3650 around the middle or so, depending on the game.
The specs that Manic needs can mostly be found with the Acer model number, but, you also need to take off the side cover and look at the label on the side of your power supply. Note the manufacturer, model #, wattage, and the output (in amps) from the +12 volt rail or rails. Basically write down everything on the label. Then he'll be able to advise you better on what you may or may not need.
edit - oops, forgot link, been up way way too long eh.
http://www.tomshardware.com/charts/g...hmarks,30.html