It's not a technical thing but a political.
Basically there's laws governing businesses. In the uk if a business pc is used to down load illegal / copyrighted material without being a license holder then the MD / Director is held directly and PERSONALLY responsible for that breach.
Thats why in most businesses there is a employment contract (i.e. I will give 4 weeks notice, not turn up to work drunk etc.) and an IT one (I will not download porn, use equipment illegally, abuse resources etc.)
And yes AppKiller requires to be installed on each PC.
Iain