IF you haven't heard of Firefox before go here
Firefox.
Basically its a web browser much like Internet Explorer but its MUCH MUCH better. It has tons of features and is probably the most secure browser there is. It'll prevent lots of spyware being installed, has a built in popup blocker and can be updated so you can install optional tools such as adblockers which can block ads on any webpage. It also has tabbed browsing so you can browse different pages from just one window. Its 100% free so you don't need to worry about registering or paying for anything.
When you install it you can import all your favourites and settings from internet explorer which will make the switch much easier. I also recommend you to install a theme and the googlebar for it. You can do this from the Tools menu and going to extensions or themes.
I been using it for 2 months now and can honestly say that its the best internet browser I ever used and have recommended it to eveyrone I know. Give it a try, you have nothing to lose!!!!