Peripheral

ive never used it but something i found

http://sourceforge.net/projects/naps/

is that the software has to 'talk to' your exact scanner.

This involves setting up the 'Twain' driver, and making sure it's the right driver for your scanner (assuming your scanner is twain compatible).

Not to mention the obvious, but most scanners come with free software to scan to pdf, so I would assume either yours cannot do that, or you don't like the apps that came with the scanner.

install primo pdf and ensure you also have acrobat reader installed.

then scan documents with our scanner and when they appear on your desktop

next print them. but instead of printing them to the usual printer, select the primo pdf printer that will also be displayed with your regular printers via the file menu print selection.

primo pdf will make/print your scan jobs to pdf files and save them to the disk.

scan to minimal kb image then open in open office which has faciity to convert to pdf file which can be read in adobe acrobat reader.

I recently downloaded and tested a plethora of different apps to do this - I was specifically looking for a easy to use app that could scan and convert multiple pages into pdf (with my old canoscan flatbed scanner)
result: http://www.koma-code.de/index.php?option=com_content&task=view&id=39&Itemid=82
scan2pdf. works great, fast, tons of options.