In separate bootable partitions or using a Virtual Machine.
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Vincenzo Di Russo
Microsoft® MVP - Most Valuable Professional
Windows - Internet Explorer since 2003
My Blog: http://blogs.dotnethell.it/vincent/
My Home:
You cannot install more than one version of IE on each bootable partition of
a hard drive. This is due to file sharing between the OS and IE. What you
will have to do is to format your hard drive into multiple partitions,
installing a version of Windows and a version of IE that the OS supports on
each partition.