I mean, Internet Explorer 5.5 is made mainly for MS-DOS based Windows versions. Internet Explorer 6 is almost identical, but made for Windows XP mainly, which is based of of Windows NT like Windows 7 is.
You know, I don't think that you could just run the setup for Internet Explorer 5.5 or Internet Explorer 6 on Windows 7, not even with Internet Explorer 7. If you did, you probably would want a virtual machine of Windows XP or Windows NT with Internet Explorer 5.5 and share the program files folder for those Internet Explorer versions with your Windows 7 host computer.
Internet Explorer 8 is the pre-installed version of Internet Explorer on Windows 7. Therefore, if you ran the setup for Internet Explorer 8 on Windows 7, it wouldn't work because either it's already installed or your version of Internet Explorer is higher than 8 and would need to be downgraded. So, anything lower than Internet Explorer 8 may not work. Maybe Internet Explorer 7, due to it being a Windows Vista IE version which most Windows Vista programs work on Windows 7. However, Windows XP programs may not run right on Windows 7 and Windows Vista. Internet Explorer 6 is for Windows XP.
Alert! Some Windows system functions rely on Internet Explorer, and if you replace C:\Program Files\Internet Explorer to be versions 5.5 or 6 instead of 8, 9, 10, or 11, then some system functions may break (mostly Internet stuff like Network and Sharing Center). Do this with caution!
Another thing: Windows XP (2001) programs still may not work right on Windows Vista or Windows 7. The reason for this is that since Windows Vista development was completely reset in 2004, the new code from Windows Vista (2007), which Windows 7 (2009) is based off of,
Internet Explorer 6 (bundled with Windows XP, released in 2001) still may not work with Windows 7.
Overall, your best bet is to make a new directory named C:\Program Files\Internet Explorer 6 and use a virtual machine of Windows XP and transport the files from your virtual machine's C:\Program Files\Internet Explorer directory over to your new directory on your host machine.
