I have to agree with kbade, I haven't run into anything to here or on the other sites speak of that required ProPack. The exception would be some of the utility programs written in a language called Python that require ProPack. Some of these are nice but none are really 'must haves' for basic Poser use. Many of the files now come with thumbnail graphics (the ones that show up in Poser's library) in png format that Poser 4 doesn't handle but there is a free utility P3DOExplorer here that will convert them to the rsr format that Poser 4 requires. Even without that, the trhings work, you just don't get the nice picture in the library.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken