Here is some stuff that I have been using on my box to make things easier and run more smoothly. I'm 95% confident they dont have ad ware, but if you get some blame it on somebody else.

In order of importance:

Firefox v1.0 - My favorite browser. Its fast, easy, and it has a bunch of tasty tools like tabbed browsing, download manager, pop up blocker, integrated google toolbar, and a bunch of other little great things that makes life just that much better.

Ad-Aware 6 - Nice ad ware detector and remover. Finds pretty much everything. I also use Spybot - S&D and a a program called Spyware Doctor.

ZoneAlarm - Detects all your connections, lets you block them, configure stuff, and warns you about hackers and things.

Winamp - For your music. Its a small play list with an easy interface.

Registry Mechanic - In short it deletes unused or un needed registry keys, and fixes the screwed up ones to improve your system's overall performance.

Kazaa Lite K++ - I dont know if you can still get this but if you can its great for obvious reasons.