Logging on and password required

HP sent me instructions on how to get my wireless printer working with Vista
Ultimate. I am the only user of this machine and did not set up accounts,
only gave the computer a name as required. The network wizard Add a Printer
feature found my HP printer but when I click to install it, I am asked to
logon and give the password to my computer. I didn't set a log on or
password but every attempt at leaving the box blank or every possible
account name and password I attempt results in the same message "The
credentials you provided are not sufficient to access this computer. Would
you like to supply different credentials?" Arrgh. Any ideas?