monitor driver troubles

Hi, I recently reformatted my computer. I forgot to install my monitor drivers early, I have a viewsonic VX2235wm LCD monitor. As a result I can notice visual differences to my monitor than before. I have tried to install the drivers from the installation CD but although it says it has installed everything I am not actually able to find the drivers anywhere let alone install them. Do I need to uninstall my graphics card drivers before installing the monitor drivers or am I missing something? My graphics card is an ATI Radeon HD 3870.

Current problems are media files playing in green and red, not normal colours and my monitor not showing smooth lines and as good visual quality as it did before the reformat.

Thankyou for any help.