New browser windows have a lot of potential problems.
I'm happy to be proven wrong though and no doubt I'll learn something along the way.
Is a simple hyperlink out of the question with a target="_blank" included into the link code ?
To do it using a frameset you include your header redirect in the framed page but target the parent frame. This loads the URL in the refresh into the parent frame, overwriting whatever is in there.
I know it isn't the same as a new browser window but it works. Then again, it uses frames and the world and his wife knows how I feel about them.
I'll have a think but off the top of myh ead I can't come up with a simple code snippet for page redirects that involve a new browser window.