I wanted to get here before you were inundated with advice to switch to Firefox (which is still an option, but upt to you). You can use the IE6 setup program, you can get it from micrsoft website or search for it on your coomputer, but this often won't run if the version you are running is more up to date then the setup program.
Option2, I have used IEFix, http://windowsxp.mvps.org/IEFIX.htm
, on a few computers with success in putting IE back to normal. I have not had a situation where it did not work, it's use jsut hasn't been required often.
Option 3: Non IE based browsers: Opera, Firefox, KMeleon, Netscape, AOLExplorer.