ATi Radeon Xpress 200M... crap. Update the drivers, no they won't make you computer run slower. Do the games lag in certain areas etc. or is it totally random? If it lags only in certain areas (esp. open areas and areas where heaps of shadows/volumetric effects are used etc.), it's your graphics card simply not being able to perform fast enough. If it's random, it could be something outside of the game.
Have you scanned for viruses/other nonwantedware? Also, try running clean-up programs like CCleaner and RegCleaner. What are the specs of your lappy? Do any other programs(/games) ever lag?