I am a seasoned db2 guy (os/390) and trying to learn ERWIN. Is there a personal edition of ERWIN (single user PC installation) like UDB 8.1 personal edition? Any other ideas where I can get my hands on ERWIN modeling tool??

There is an evalution copy that you can download on the CA website. I don't know how long the evaluation period is, but if you are willing to reinstall Windows (or periodically restore a backup of your hard drive taken before you install Erwin) you might be able to get around the limitation.