Win XP system login accounts

Hi, where does XP store it's user account data and passwords? Is it in Windows/Repair/Sam?

Windows, not just XP, stores passwords for local accounts in file C\Windows\system32\config\SAM

Not really a forensic question, but I'll play.

Also, anyone know a quick and way way to change a username in XP which apply to the relative user folder name e.g. CUsers/[Username]?

Changing the username will not change the folder name for the user. The easiest method would be to create a new username and copy the original account, then delete the old account.

Use THIS method to copy the account.

Windows, not just XP, stores passwords for local accounts in file C\Windows\system32\config\SAM

Windows NT based systems (i.e. NOT Win9x/Me) to be more accurate.

Also, anyone know a quick and way way to change a username in XP which apply to the relative user folder name e.g. CUsers/[Username]?

What do you mean by "quick and way"?
You can duplicate an account to a new name
http//www.cpucare.net/OS/XP/How%20to%20change%20usernames%20in%20XP.htm
and then delete the old one, but the usual procedure seems not to me that much complex
http//windowsxp.mvps.org/userpath.htm
http//www.ghacks.net/2011/03/28/how-to-change-a-windows-account-name-and-user-profile-folder-name/
Of course hardcoded paths in third party apps won't work anyway and will need to be corrected manually.

Also, possibly you may want to try this
http//www.forensit.com/desktop-management.html

jaclaz