Internet Explorer 7

Internet Explorer 7 shipped as the default browser for Windows Vista and was made available for Windows XP with Service Pack 2 or 3. Internet Explorer 7 discontinued support for Windows 2000 or earlier with Microsoft citing required security API improvements that were not available in prior systems.

It includes tabs to browse multiple webpages in one window.

2000 support
This does not work on Windows 2000 by default as it is unsupported, however, blackwingcat tried to run it on 2000, and got it to open, but nothing in it worked and typing internet addresses in the Explorer bar doesn't do anything. However, in a different MSFN thread, blackwingcat said that IE 7 (and 8) require the Luna interface, which is not true as it can run just fine with Classic Theme enabled.