Yes,

"explorer.exe" is windows explorer and is normal.

"iexplore.exe" is Internet Explorer and you will get one running for each instance of IE you have opened. That is actually clicking on the icon to run the program again, NOT opening something in a new page or window.

So, if you lgin and go on the net for a while and find that you have more than one iexplore.exe running, it means that you are infected.

As your problem is probably a trojan I would suggest that you get a trial of Moosoft's "The Cleaner".

AVs are not very good at detecting trojans

Good luck