A better choice is Kazaa Lite. Basically it's a variant of Kazaa with all the spyware/adware ripped out. Lets you run Kazaa without the hassles, though the Kazaa interface will still pop an ad on you once in a while.
www.kazaalite.com
I highly recommend LavaSoft's Ad-aware. Run it, and it hunts down and removes the spyware/adware junk.
www.lavasoft.de
Finally, most of my browsing nowadays is done from Opera (95%). Most sites render fine in it, though sometimes I do switch back to Internet Explorer. Opera is just lightning fast compared to IE and has some great features for browsing. E.g. if I get a list of new messages, I can ctrl-shift-click on the ones I'm interested in, and it'll pop open a new tab for each message in the background (of the same window). Then I just read each one and close each tab with a ctrl-F4. It's great for "industrial web reading," like reading a bunch of stories from ESPN.
The reason I even mention Opera here is that a lot of spyware/adware can't get into it, unlike IE. One of Opera's best features is "disable pop-ups"! which gets rid of the annoying pop-up and pop-under ads as you visit web sites. There are hacky little tools for IE which try to do it, but Opera has it built-in and it works reliably.
The downside to Opera is that there is a small ad rectangle in the upper-right corner. You have to buy it to remove it, though, frankly, the ad banner is unobtrusive to me, and it's well worth the money.
www.operasoft.com