Logging onto XP as an administrator

I’m a XP home edition user. I recently installed a printer but the installation required me to log on as an administrator, and was incomplete.I thought that I was administrator by default. 1) How can I determine if I have administrative privileges? 2)If not, how can I grant/log on with these privileges? I currently don’t use a password. There must be a way without reinstalling XP. Thanks, Steve O. Sloday@swbell.net