I didn't say always redirect. I said, check if you need to redirect before you print the header. Then if you need to redirect, redirect. If not, print the standard HTML.

If someone has already filled in the form fields on a previous invocation of the script, I assume you don't really need to prompt for them again and you can just check the username and password and redirect as necessary. (Though I wonder why you need the redirect and don't just change the form action to the new script, but that's a different story.) I don't know though; I don't have the right font installed to read your variable names appropriately. (I can read your database password just fine though.)

If you want to print the normal page and then redirect, sorry. HTTP doesn't really work that way.

Honestly, you're making this a lot more difficult than it needs to be, especially trying to manage the use of multiple separate programs and trying to shuffle variables back and forth between them. CGI::Application, CGI::Prototyped, Maypole, Catalyst, and Jifty are some of the best ways to manage this type of program flow and it would be a very good investment of your time to learn one of them instead of trying to do this all yourself.