Dell Dimension 4600 Problem?

Okay, so i have a dell dimension 4600, and whenever i try to start up the computer, i go to start windows xp or whatever its called, I'm not very good with computers to be honest :p so just bare with me. Anyways, the computer just restarts and goes back to starting again and gives me the options for safe mode, setup utility, startup windows etc., I've gone to all those options and it just restarts all of the time. I went to the bios and i cannot touch anything because the security has an admin password which unlocks all the options to access, and without the password, i cant access anything on the bios including a bootup to restart the whole entire computer back to normal, How can i fix this problem, because i cannot access my computer at all, Do i have to open up the computer and take out the pins from the password jumper and take out the battery from the motherboard, or what other options do i have? if i have to do option number one which i stated above, can someone please find me a documentation of how to take out the battery from the motherboard and taking out the pins from the password jumper.