Well, if you know what your doing, even IE can be safe ( since i only use IE, and never had any problems )

also get Spyware Blaster.
While Spybot and Ad-Aware remove spy/adware, Spyware Blaster will try and keep it off your pc:

The most important step you can take is to secure your system. And SpywareBlaster is the most powerful protection program available.



Prevent the installation of ActiveX-based spyware, adware, browser hijackers, dialers, and other potentially unwanted software.
Block spyware/tracking cookies in Internet Explorer and Mozilla/Firefox.
Restrict the actions of potentially unwanted sites in Internet Explorer.

SpywareBlaster can help keep your system spyware-free and secure, without interfering with the "good side" of the web.

And unlike other programs, SpywareBlaster does not have to remain running in the background.

Download:
JavaCool Software