If u want to unistall the drivers all u have to do is go Device manager
look for display device (unbox the 2nd or 3th of the list) it should say Intel 945 bla bla bla go there look for unistall device. reinstall with the CD of drivers.. or download em from i dont know where :D ................... But in your case u are worried about the decrease in performance of some games... let me guess Counter strike 1.6? some games wont increase their performance in terms of FPS, they will decrease becuase thos games run under a rendering device named OPEN GL, which is not supported by the MDs... so u u have to decide DRAMATIALLY increase the performance of DirectX apps or go for OPEN GL summary; u lost performance not becuase one driver has been installed above the other... ist becuase the game u r trying to run its not supported by the MD... other games will run WAY better INTEL 9xx SOLDIERS SANS FRONTIERS
