If you have IE8, unlike in previous versions, it'll run TWO iexplore.exe processes from the get go. Every new open tab will add another iexplore.exe process.
That's how IE8 works.
Now, you don't want to change iexplore.exe name for two reasons.
It's a part of Windows and it's not a good idea to change system files names, since some other Windows components may be looking just for that name.
Why would you want to do it anyway?
Now, if you have iexplorer.exe file on your computer, then it's infected.