Stephanie,
To be on the safe side I have to say no. You risk failing the exam if you use 3rd edition prep materials. So I cannot recommend it. (My lawyers make me say this.)
However, from a broader point of view you can probably use the general information in the book and you will still learn a lot. There are some significant changes between the 3rd and 4th edition PMBOK Guide (42 instead of 44 processes, new/changed earned value formulas, etc.) but the PRACTICE of project management and our general approaches have not changed.
So even though I cannot really recommend it, you could go ahead and use Rita's 3rd edition book if you use caution in regards to all these changes in the new PMBOK. Read Appendix A in the PMBOK to learn about the changes and also read the article that I wrote here:
www.cornelius-fichtner.com/index.php?opt...tid=38:pmp&Itemid=60