Windows 7 with service pack 1 comes loaded with Internet Explorer 9 by default. You can revert to Internet Explorer 8 by following theses steps:

• Open "Programs and Features", formerly called "Add or Remove Programs", by clicking on the start button (or by holding down "Windows key + R" to bring up the run menu) and typing appwiz.cpl and hit enter. Click on "View installed  updates":
• Select "Windows Internet Explorer 9" from the update list and click "Uninstall" 
• Reboot your computer and you will have Internet Explorer 8