Generally, as we cannot determine the intentions of having this knowledge, we cannot disclose this information.
Hope this helps!
Didn’t think of that… 😉 bottom line is we need more information.
If you are asking how to access the default administarative account in a Microsoft OS, then support.microsoft.com or technet.microsoft.com has articles on how enable or access the local administrative account for Windows XP and Vista. For a specific answer, see above.