No, the router does not not store computer or network passwords.
The only passwords the router stores are your wireless password and the password to the admin GUI.
Both of those are stored encrypted.
As a work around on Win 7 or Vista you could enable the administrator account, login with it - Control Panel - user accounts- manage another account .. then reset the password for the original account, http://www.howtogeek.com/75470/how-to-enable-the-hidden-windows-7-admin-account-using-the-registry/
UPDATED the link, you will need a windows 7 DVD to do this work around
HInt. Set up at least one additonal account for emergencies with Administrative power.
Make sure to backup the encryption keys for files.