Just my opinion...
I bought many books and many guides about WDW, they are great and i think that it is really indispensable, My vote is:
Unnoficial 2003 and 2004 : Great book, good ranking of each attraction, resort, restaurant, shopping etc....they also include reader comments which are very interesting, funny and helpful . You wiil find many tips.
to lentesta > Even " ectasy and agony" i will be there with my little 5, Could you give me an autograph in Mousesavers meeting ?

)
Tour Guide Mike: Very very good, yes, it is difficult to navigate, but Mike really know many things about WDW !!
Birnbaum's Walt Disney World 2003: The park maps helps a lot, great pictures.
Walt Disney World with Kids 2003 : This book helps alot if you are travelling with kids, how to choose the rides, parks, recreation and resorts, great guide !
I know that it isn t in question but i would like to recommend Street Finder, it is great for who doesn t know how to drive in Orlando
Please, take a look to my travel kit:
<img height=300 src=http://fotos.aol.com.br/adAlbumFotoSizeShow.aspx?Album=3518&Item=DSC00076.JPG&Largura=446&Altura=297>
The worst part is that i spend a LOT of money, but it really worth, i think now i will be ready