when if there moment like when u in some1 admins account in xp but when u need to change the pass in that when u dont knowng the pass u can use this way....
go to CMD
Thn type like this
net user <space><user account name><space><new pass>
Eg- net user nic asdf
try it
go to CMD
Thn type like this
net user <space><user account name><space><new pass>
Eg- net user nic asdf
try it

anyway thankz