Going to upload my work to Lulu for print ,but all the page file pdfs need to be one pdf in order to get the bleed effect. Adobe won't let me download the trial version again and the program is hella expensive. Is adobe acrobat the only program that can combine pdfs?

Hm, it's the only one that I've heard of that will do it... there are free pdf-makers out there, but they only convert a document from another source like Word. Google has nothing? :(