Are you using DVDs for your video? If you are, you most likely don't have a reason to render in HD because DVDs are SD (720x480). It all depends on the source and effects you use, but in most cases you should render in the same resolution and fps as the clips you import. If you can give us more details about your project, we can certainly help. Welcome to the org!
Also, your best bet for finding a good new AMV is to check the AMV Announcements forum:http://www.animemusicvideos.org/forum/viewforum.php?f=3