You are the owner HD5750, right?If you have Dirt 2 with u, can u run it's benchmark at these settings:
Resolution:1280x1024 or 1440x900(Which ever u could do easily)
Anti-aliasing:4xMSAA
Rest Settings: Go to graphic options, underneath the resolution refresh rate and Vsync, their would be written "Choose Preset", go in it and select High along with Above Settings;
Run the benchmark and please let me know that how much fps u get on average...thanks!