lock-out

I feel just straight stupid here, but Im in a jam .... check this stupid move ... I have an optiplex 210  and am running XP ... well I was looking for a little more security and ... you guessed it I am now completely locked out of my computer ... it seems to me that I remember the password, but I must be wrong. I dont know whats going on as I have used the password before, all I did was install a better surge protector and some better speakers .. things that should have no effect upon this situation but I am here.

now what I did do in the beginning was to go into the setup  at the start and install some passwords so now at this point I cannot do anything at all until I can figure out a way to bypass this and reset the machine back to the way it was previously. I have learned my lesson please let there be an easy fix for this problem.