Attached Link: http://www.curiouslabs.com/article/articleview/1020/1/84/?df=1

You can download the service release 4.1 at the link. It updates all versions of poser 5 so you don`t need to know which version you have, as long as your version number is lower than 5.0.4.325. You have to download the service release 3 figures updater too (newer versions of the figures werent needed for service release 4) unless you have already downloaded these.