1- You need to find your Notebook or PC, Manufacture & Model.
For example I have, (Manufacture: Sony VAIO / Model : VGN-CS16s)
2-Then move to their official web page , eg: http://www.sony.co.th/support/product/VGN-CS16S?site=hp_en_TH_i
3-Go to download section
4-Choose your operating system, (in your case "Windows 7"
* Accept any agreement term and select it.
5-Keep downloading your , Graphic card, Sound card, ...