The May 15th issue of the Support Alert newsletter has an interesting article on converting PDF files into Word documents. Initially, the newsletter author, Ian Richards, tested a couple free online conversion services, then he got readers with seven different commercial products to convert his sample document.
He called the results "fascinating" and found that "the products varied markedly". The most expensive product produced one the worst conversions. Overall, he likes Zamzar, a free web-based conversion service, saying "Most users who have only a casual need to convert PDFs to DOC should save their pennies and use Zamzar rather than buy a commercial product." The list of file types that Zamar converts from and to is huge.
The original PDF used for the tests was posted at techsupportalert.com, but it's no longer there. So, I searched news.com and ran across a PDF formatted profile of someone named Kathy White (I haven't read the document) from 2002 that seemed like it might be hard to convert. You can see the results of the Zamzar conversion here michaelhorowitz.com/zamzar.test.white.doc.
Looks pretty good to me.
Update. June 5, 2008: Someone just told me about another review of PDF to Word software and services at www.freewaregenius.com, How to convert PDF to Word DOC for free: a comparative test. The comparison testing, done in March 2008, included six products, all freeware. The favorite was the Koolwire.com service.