I know this has kind of been answered already, but I'd like to add a couple comments here.
The article on the Rob Cottingham web site to which the URL in the prior post points suggests AbiWord, which is an open-source word processor. While I don't object (in principle) to using AbiWord for this task, I would like to point out that my own experiences with AbiWord have been somewhat off-putting. Now, in fairness, this really has to do with the available means of porting AbiWord to Mac OS X and the Aqua environment, and isn't by any means an indictment of the programmers who wrote the thing. However, it just acts funky and flakey, not always rasterizing type correctly, getting the leading and kerning not just a little off, but just flat totally wrong, and there are also some performance and stability issues.
Not that it's 100% better, but you might want instead to try using NeoOffice, which is a Mac OS X port of OpenOffice (which, if you read the article and the follow-up responses to it, one of the posters made reference to). I believe it will (though I don't know for a fact) open WordPerfect format documents.
Ultimately, however, the best option -- short of getting the person who's giving you these WP documents to switch to something modern -- would be for them to save a copy of the document(s) in question as Rich Text Format files instead. These are far more easy to work with, and any even half-baked word processor can handle them. TextEdit natively works in this format, btw.
