Machines running on least privileges are significantly more secure than those running with full privileges. The “Microsoft Security Intelligence Report” (SIR) (based on the first half of 2008) stated that globally, the biggest internet security threat is Trojan Downloaders.
Microsoft was able to provide a ranking of the online threats that posed the greatest risk globally during the first half of 2008. Trojan Downloaders ranked as the largest threat while Exploits came in at number ten. These are all threats that can be reduced significantly by limiting the administrative privileges on user computers.