Administrator Account - User Name / Password Problem

I don't know how I could be so stupid. I bought a PC with
WINDOWS-XP pre-installed. New to WINDOWS-XP,I then set up
an administrator account with a user name like "Admin Acct
Alex" or similar. Unfortunately I did not write down the
exact name on a sheet of paper for remembering it.
When I tried to log on to the administrator account by
using every thinkable combination of the name I might have
entered, I did not succeed. I had hoped that entering just
the password would be sufficient to get access to the
system. I definitely know the exact spelling of the
password I had entered, because I use this password for
many other purposes.

What can I do? Would I actually have to run the "Recovery
CD-ROM that came with the PC" and start all over again?

Alex