AdwCleaner is a compact and portable tool which can help you to remove toolbars, adware and similar browser-based pests.
It's easy to get started. Click "Scan" and in a minute or so the program displays everything it's found, organising the report into several tabs: Services, Folders, Files, Shortcuts, Scheduled Tasks, Registry, Firefox, Chrome.
AdwCleaner was quite aggressive on our test PC, highlighting some applications we'd consider safe. It also did a good job of detecting more dubious files, though, and you can always tell the program you'd like to keep something. (Although everything is marked as "Delete" initially, and there's no "Clear all" option, so if you only want to delete one out of 20 items then you'll need to clear all the others manually.)
Choose the Cleaning option, and the program warns you that it'll have to close everything and restart your PC to remove the chosen items. That might be a little inconvenient, but it's the best course of action, and you can always hit Cancel if you change your mind.
AdwCleaner successfully cleaned our test system, and if it's not quite enough for you then the program can optionally reset a range of Windows settings: proxies, winsock, TCP/IP, firewall, IPsec, BITS, IE and Chrome policies.
AdwCleaner did a good job of detecting and removing adware for us, but be careful, it can highlight legitimate programs too. Check its report carefully before you delete anything.