first of all enable automatic updates to ensure your computer is secure, it almost sounds like your computer is polluted with malware or a virus
the newest service pack is #3
http://www.microsoft.com/download/en/details.aspx?id=24
then install Microsoft security essentials,
http://windows.microsoft.com/en-CA/windows/products/security-essentials
then try installing either ie8 or firefox 8
the newest service pack is #3
http://www.microsoft.com/download/en/details.aspx?id=24
then install Microsoft security essentials,
http://windows.microsoft.com/en-CA/windows/products/security-essentials
then try installing either ie8 or firefox 8