[Know Ur Lingo]
are the rogue security softwares i.e. malicious softwares pretending to be security solutions working against viruses and worms. It pranks user to feel its need to make the machine secure against some attack or virus infection and gets installed.
are the malwares which hold the infected machine/service/data as hostage, and demand ransom for disinfecting the hostage. ;)
if you think you have been infected by such malwares, or wanna minimize the risk of getting infected beforehand... you can use security solutions like
Microsoft Malicious Software Removal Tool : http://www.microsoft.com/security/malwareremove/default.aspx
Or you could get your file scanned by Kaspersky Free Online Virus Scan http://www.kaspersky.com/scanforvirus