Ive been out of D&D for a few years. All my stuff is 3e. I was told there was a document that contains all the changes made in 3.5. Is there a document that will allow me to adapt 3e without having to buy all new books (again)? :\
not really. you can use that document to update characters and things, but then without the rules in the new books they won't fit the 3.0 books you have. you could just use the SRD though.
Some folks don't even bother buying the core books. If you're trying to play 3.5 mostly from 3rd edition books, pay special attention to the changes with spells, ignore the ranger and monk classes as listed in the 3.0 PHB in favor of the one in the SRD.