The best Windows password "recovery" tool is a Linux bootable CD or USB drive (or even floppy) with a couple of tools to access the SAM on almost any version of Windows NT. Trinux or Knoppix are the most common versions.
I have used it successfully up to and including XP and Server 2003 (not domain controller), and it will probably work with Vista - though I haven't tried it myself (yet). Not sure about 64-bit versions of Windows either, although it should work on 32-bit versions running on 64-bit capable processors.
It works by extracting the Security Accounts Management (SAM) database from the disk, allowing the password for any account (including administrator) to be changed and the modified database written back - even on NTFS partitions.
Given this tool and physical access to any (non DC) Windows PC / server, it is possible to gain complete access in a few minutes - longer if the CD / Floppy is configured non-bootable in the BIOS, necessitating the preliminary step of re-setting the BIOS password via the appropriate hardware or software mechanism.
Use with care!
SD