A lot has been written on the opening of new browser windows and how you shouldn’t do it because it annoys and confuses just about everyone, especially the blind and visually impaired. However, I feel that, while it can be over used, it definitely has its place.
For instance, if I am filling out a long and complex form, and I click a help button for a field, I don’t want to be whisked off to another part of a page, or to another page entirely with out an obvious way to get back. I don’t want to have to worry about my form session being preserved.
When a new browser window is opened, I can flip back and forth between the form and the help window as much as needed, and when I’m done, I just close it. To be honest, I don’t find them to be nearly as annoying as some writers claim, and in fact, they can be quite convenient when used right. Of course, this is just my opinion, and less experienced users, or users of screen magnification might have a different view. Still, it may bare looking into. My personal feeling is that whether or not a user will have difficulty with spawned windows is probably less a question of disability and more a question of experience with the web.