How chuffed am I? Very!
Because the laptop is quite old in terms of laptops and there is no drivers for windows 7 on the samsung site available for the Samsung Q45.
I finally found a solution to the annoying birghtness keys not working in windows 7 on my Samsung Q45 laptop. After failing after several reinstalls of windows 7. I persisted today and found that installing this version of Intel VGA Driver solved my problem.

VGA_Intel_GM964_ v7.14.10.1409

If after installing it doesn’t work go into the control panel > Device Manager > Display Adapters then double click the Mobile Intel 965 Express chipset Family and under driver uninstall driver then install above driver again. Hope this helps others as it helped me.