This page is also interesting, the part on how you can prevent the
furtive installation of BHO by modifying the security on a unique
key can interest some people I think....

CIACTech02-002: Microsoft Browser Helper Objects (BHO) Could Hide Malicious Code
hxxp://www.ciac.org/ciac/techbull/CIACTech02-002.shtml

etherlord