Unfortunately xpdf, evince, acroread etc. cannot highlight text or add comments to PDFs. PDFedit cannot select text properly for many PDFs.
However, there is a nice and free alternative, but you need wine to run it: PDF-Xchange-Viewer [http://www.docu-track.com/download/PDFXVwer.zip]. There's also a thread on this on the SuSE forum.
Update: Apparently with newer wine versions you don't need the script below anymore, since opening files out of the PDF-Xchange-Viewer works directly. Also see the comments below on this.
After installing the viewer, the following script handles file opening: