Windows XP vs 2000 - SAM related

[Steve]

Just a quick question, I forget the architectures of NT/2000

1. Is it true that if you remove the SAM database via an alternative boot,
your box then has default passwords ?
    ie. Empty guest account, Empty Administrator account

2. Is it the same in Windows XP Pro ?

3. How/Where does one find the "registry database" in NT/2000 and XP Pro
under command prompt ?

TIA ;)

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