The newest release of Lavasoft's Ad-Aware anti-spyware application sports an updated interface, faster scanning, more configuration options, and -- finally -- automatic updating of its spyware database files. The free version is still a standout, but if you want even more features, you can pop for a couple of paid versions. A Microsoft Windows Vista version is not available yet, but is in production.

Read more about the new Ad-Aware and download your free copy here.

Webcast (mp3) (Windows Media)

Stay away from Vista... it's horrible.  

Adaware is still the best that's out there.  Took it for a test drive today on my re-loaded XP and it's awesome.

Disclaimer: I ain't no expert.

That said, Ad-Aware hasn't warranted major consideration at our house for some time. We still keep it updated and run occasional scans with it, as a 4th or 5th opinion, but that's it.
At one time, the free Ad-Aware and Spybot S&D utilities were the only anti-spyware scanners on our machines. Those days are long gone. So is Spybot, uninstalled more than a year ago.
We now run a paid-for CounterSpy for real-time protection (Spy Sweeper and Spyware Doctor would be alternate choices), free AVG (Ewido) AS, free SUPERAntiSpyware, free AVG and Sophos Anti-Rootkit scanners, with the free SpywareBlaster running quietly in the background.
I'd love to see Ad-Aware post much-improved results after some rigorous testing by trusted outsiders. Until then, I'm happy with our current configuration.

Spyware Terminator is really good as well, it's also freeware. I feel it's better than Ad-Aware. And yes, Vista is crap. Won't be any good until after the first service pack is released.

http://www.spywareterminator.com/

Quoted from prairiejock

Stay away from Vista... it's horrible

Interesting. I have Vista on a Toshiba notebook, a Dell E520, a Dell 4700 and a custom-built Touch Systems PC.  Aside from an outdated WiFi driver for the notebook, and a not-quite-certified Creative Labs soundcard driver for the 4700 -- both of which were fixed with an update download -- I have had no problems with it whatsoever.  I'm interested in what prompts you to advise everyone to "stay away".