Installing AMD Radeon drivers in Linux: Example from HP 4331s with Ubuntu/Netrunner

Last week, I tested Netrunner on HP
4431s Pro-book laptop (2.3 Ghz 2nd Gen. Ci3, 4 GB RAM, 500 GB Hard
drive, Windows 7, 1 GB AMD Radeon HD 7470M graphic processor). This
laptop belonged to my friend and he came to me to resolve a couple of
issues:

Virus/Malware
problem and slowing down of Windows 7 - the antivirus software
installed could not remove, neither it could be deleted manually.