Sorry upgrading a 10 year old version of Web Wiz Forums by just copying over files would not work as there are many linked changes over that time.
There are also improvements to features, performance and security improvements that mean its important to make sure you are always running the latest version, especially with a web application that is connected to the public internet.
As a hosting provider we see websites that get hacked all the time and used for malicious activity such as phishing and spamming due to the website owners not updating the applications they have running on their websites.
If you are using SQL Server you can always change the password for your SQL Server database user, or create a second user for the database and use the new user when upgrading. The new user will need to have DataBase Owner (DBO) rights over the database.