The other night I needed to produce a PDF from a Windows 98 computer. Most of the PDF print engines that I found were requiring Windows 2000 or higher, so I was quite surprised when I came across CutePDF Writer. The software installed easily and did the job well.
The application is only a 1.5MB download, but it does have a dependency on GPL Ghostscript 8.15 (a 5MB download).
This software is listed as being free for both personal and commericial use.