Windows XP Windows XP Home and bypassing user account passwords

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OK. I know this seems wrong and not moral and all of that. But I have reason to suspect a family member of doing something they shouldn't be doing. lol, sorry so cryptic. This person can not be trusted to tell the truth if confronted and this is something that if is true and is not stopped could cause harm within the family. Both of our user accounts are administrators, but mine is the actual owner account. They recently password protected their account. I need to check their internet (Internet explorer) history. Is there any way I can do so not being logged in to their account? Is there a way to bypass the password w/ them not knowing I was on? That is all I need to do, check the internet history. It isnt criminal, but it is vital to us as a family. Also, if you keep guessing and getting passwords wrong from the Welcome login screen, will they ever know? Thanks for any help you can give!