The U.S. Department of Justice doesn't think this is such a great idea, but it's certainly useful for the Windows user who doesn't want to think too much about how the computer works. With MS Office, you can have a menu pop up on the right side of the screen every time you start up. As for compatibility, Word 2000 is backwards compatible with its predecessor, as well as WordPerfect, so you can share files with colleagues who haven't yet upgraded. There are tons of legal templates out there, from Microsoft as well as third-party vendors. Still, if you're attached to WordPerfect, you certainly can survive in a sea of Word users.
Conversions are pretty easy, plus there's that great option of producing PDFs.
Otherwise, there's not a world of difference. In terms of value, WP Office gives you tons of add-ons that you'd have to pay extra for using Microsoft's suite. Then again, you might go your own way completely, and be one of the relatively few lawyers who use Apple Macintosh computers. For them, the only professional office suite is Microsoft's Office 2001, and, oddly enough, it's the most compelling in some ways. It's one of the big ironies of these past couple of years that Microsoft, previously an avowed enemy of Apple, writes nicer software for the Mac than it does for its own Windows operating system.