I think this post was old enough to qualify for our "don't wake the zombies" rule, but now that it's up and lurching about, here goes.
I have no clue what rundll32 was supposed to do with opening PDF files.
There are number of utilities that can "open" (as in display) and read (as in processing the contents) PDF files. The most famous of which, of course, is the Linux edition of the Adobe Reader application, downloadable from their website. Some people think that the Adobe app is too fat, too insecure, or just prefer open source, however, so there are also a number of open-source PDF display apps as well. I commend you to Google for details.
Linux is based on Unix, so it inherits a lot of text-processing support (which is what Unix was originally designed for). There are utilities to slice, dice, reformat, scale, rotate and otherwise manipulate documents in PDF, PS, TeX, and many more text and graphics formats as well.