If you're just storing your passwords and usernames in a document on your PC, then you're leaving yourself vulnerable to attack from hackers and spyware that can easily extract such information via the net.
The most secure solution is to store such data in a password protection utility such as Password Prime. The application works by memorizing passwords and usernames and then allowing you to use one password to recall them all every time you visit secure sites. Password Prime adds itself to your Windows shell so that adding new passwords and usernames is easy. Of course, everything is encrypted via complex algorithms to ensure that your data is not compromised.
In addition, each username and password entry includes quick links that take you directly to the website or location where your password is used. The plus side of this program is that it's completely free and there doesn't seem to be any adware supporting it. However, this also means that you have no comeback if your security is compromised. The developers assure that your credentials are protected by their own "System Sentinel" but fails to reveal what kind of encryption it uses.
Password Prime is a simple to use and free password and username manager that will save your precious and tedious time spent entering the same old usernames and passwords.