Hi! Welcome to Linux country!
Since you are used to running Unix your transition into the Linux fold will be almost seamless. You'll have a different shell by default. Most distros use bash...with Unix I imagine you are used to korn. Minor differences in syntax and such. You can add or use whatever shell you are used to though once you have installed.
There has been a port of IE to Linux called aptly enough "ie4linux" (http://www.tatanka.com.br/ies4linux/page/Main_Page). For the Word/Excel etc the distros include something called OpenOffice. It is just as powerful (if not more so) than MS Office and includes a word processor, spreadhseet, presentation software, database etc. Layout is very similar to Office.
Which Linux distro should you run? Opinions vary as often and as widely as what car someone should drive. The primary ones are Ubuntu, Fedora, and openSUSE. However there are tons out there to play with. A good site to visit is Distrowatch (http://distrowatch.com/. It has write ups and reviews of all the distros currently available. The main thing about Linux is there is NO charge to download and use. They are all free.
Personally I've installed and used quite a few. I favor Ubuntu because they have a very clean and solid installation. They also have a great repository of documentation as well as a huge user community at ubuntuforums.org. It is an excellent version to get your feet wet with. http://www.ubuntu.com/
Reference your computer's hardware all of the Linux distributions will work fine.
If you have other questions let me know, will be happy to help.