If you want to run IE6-8 on Ubuntu (or any other Linux distro that support VirtualBox), see this blog post: Use Internet Explorer 6, 7 and 8 in Ubuntu
Use Internet Explorer 6, 7 and 8 in Ubuntu11. May, 2011
IE6: Time to Say Goodbye7. March, 2011
The large group of people who want to get rid of IE6 just got another member: Microsoft. Good luck!