Easiest or Best Free Way to Scan to PDF in Windows XP

Easiest or Best Free Way to Scan to PDF in Windows XP

I have a scanner (part of an HP PSC 1315 multifunction printer, if that makes any difference). I've recently paved my Windows XP machine and appear to have lost the software for the printer. This has meant that I have to use Windows Image Acquisition or Microsoft Word to scan images and documents.