I just read an intersting article on osOpinion about the Microsoft's file format lock-in tactics. Basically, it discusses Microsoft's current dominiation of the Office Suite environment, how it is largely due to their proprietary file formats that prevent people from switching to other suites (hence the term "lock-in"), and where this is headed in the next versions of Office and even Windows. Hint: It's not good.
The bottom line is that now is the time to begin looking at and switching to alternatives. I recommend OpenOffice to get started. You can and should read the full story below.