Unable to logon to the main administrator account on XP

Hi...

I was having several computer problems with XP on my
computer.... I was told that it might help to just create
a new user account, and work on that one instead.... well
i did so, making that new one an administrator account,
and renaming my old account and changing it to limited, so
i can use the name for the new one..... I dont know what i
did, but somehow i got logged on to the old account, that
is now a "Limited" account, and when i tried to get into
the other it wont let me, i've tried everything, and there
is nothing I can do because im stuck on the limited
account I made, and dont know what name the computer is
using for the administrator account....... What should i
do? I would go as far as just re-installing windows xp all
together, but im hoping there is an easier way, plus I've
lost my Windows XP cd, or any others i've had =s