HijackThis is a no-frills tool to detect and remove suspicious elements from your web browsers.
This tool works by scanning your browsers to see what might be lurking in them. It gives you a clear and straightforward list of the results, sorted into different categories. These categories will mean very little to you at first, but if you click Info in the main HijackThis interface, you'll find a guide.
Each HijackThis entry has a check box. Check this and hit Info on selected item... and you'll get more details on what the entry is and what effect fixing it will have. HijackThis is definitely a tool for user who know what they are doing. Although it does give you information on the results - and warns you if an option could have dangerous results - the decision to delete or change is ultimately yours.
HijackThis is a good tool, even though it's not going to win any prizes for looks. It has plenty of options, like an ignore list for items you know to be safe, and plenty of extra tools, like the ability to delete a file on reboot and open the ADS spy. All your actions are also recorded in a log file and automatically backed up.
HijackThis is basic and functional, but a practical and efficient way of keeping an eye on browser elements.