You can run most Windows programs on Linux under Wine. Wine is not an emulator. (Get it? W I N E.) It is an open-source replacement for the Windows APIs that runs under Linux - so programs run at essentially full-speed.
There is some fiddling with settings that is needed to get some programs to run. But there is a low-cost commercial version that comes with support and tested configuration files for the Office suite and a large number of popular programs.
The latest beta version even runs many popular games including Half-Life 2, CounterStrike, and World of Warcraft.
Yes, it runs Internet Explorer, which is, of course, an essential webmaster tool. (For checking compatability.)