Well a lot of people have heard of Microsoft Office, but there are alternatives like OpenOffice, an IBM Lotus Symphony; just to name a few. I personally use OpenOffice when possible along with Zoho (like Google docs, a online office suite and the ability of to collaborate too). These are free and open source alternatives to Microsoft Office, in many cases just a simple registration is required. There are many advantages to using these alternative office suites, one is price, most of them are free and the other is size; installed most of them are much smaller then Microsoft Office. Another good thing about them most of the alternative suites is it can open, read and modify Microsoft Office files. But in any case you have the power of choice to use these suites, so give them a shot, you maybe pleasantly surprised.
Links:
http://symphony.lotus.com/software/lotus/symphony/home.nsf/home
http://www.openoffice.org/
http://www.zoho.com/
