The 9200 helps get you Vista or 7's AERO but not much else. I see you found that lower resolutions help so keep doing that but this is not a driver or such issue. It's simply a video solution that is not a gamer's choice.
Many new games like Modern Warfare 2, Resident Evil 5 and Need for Speed Shift are not running smoothly on my PC, these games do run smoothly when I set the resolution of these games to 800x600. I already used some PC/game booster software but none of this worked. I also checked the recommended system requirement for these games and my PC specification is also good to meet the recommended system requirement for these games.
My system specification:
Model: HP Pavilion dv5 Notebook PC
Processor: Intel Core2Duo 2.00GHz
Memory: 3 GB
HDD: 230 GB
OS: Windows Vista Home Premium SP2
Graphics: NVIDIA GeForce 9200M GS (1521 MB)
I also checked the CPU and Memory usage of my PC during any of the above games were running and my PC CPU usage was 60-70 percent and my PC Memory usage was around 2 GB.
Any help will be appreciated.