• sysprep is used to prepare a drive. It does a shutdown after finishing, and you should Ghost the drive immediately after, WITHOUT booting into the OS.
• The first time you boot after running sysprep, it goes through the OOBE (out-of-box experience) screens. From this point on, the user has 30 days to activate the OS. (so, if you're preparing a Ghost image, you want to avoid doing the OOBE stuff, because that's for the end-user)
  • If you are doing an internal distribution, it is sometimes okay to run NewSID instead of sysprep. This keeps the license keys intact, but does the core technical stuff needed (regenerating a new SID).
• If you need to boot into the OS, just to fix a mistake before Ghosting, press Shift+Ctrl+F3 at boot to enter Audit Mode.
• Alterately, you can go through the OOBE screens, make changes, and then run sysprep again. However, note that you can only do this three times, because the 30-day-period can only be delayed three times. (to avoid people using sysprep to indefinitely delay activation)

External links

• Sysprep Technical Reference
• really good sysprep guide
• offline sysprep