This is one must have tool to help you out if you are struggling to remove some virus from your computer or trying to kill some stubborn process. It just lists out the processes in your system which are using the key areas of your system like the RAM, registry, hard drive. If you wish you can create a log of all such files. To use this you don't have to install this to your system. You can download & directly run this tool.For me it has helped removing Trojan Horses from my system. A month ago my computer was under attack of some Trojan Horses .I tried removing them using Kaspersky, PCcillin, zone alarm. All of these antivirus were able to detect the virus but not able to disinfect or quarantine or delete them. Then this was tool i used to kill the virus processes and delete them manually.
On many other occasions when i needed to remove some malicious viruses I used Hijack This. But unfortunately this is not one of the tools which can be used by a novice user. You must have some experience to use this as u can not just kill any process . The list of processes shown by this tool is also in such a format which can't be read by some novice user.