start>rightclick Computer>manage>users>users>rightclick administrator>properties>General Tab>uncheck"Disabled"
then set a password, right click administrator>set password.
open command prompt as administrator (right click method) and type in this:
net user administrator /active:yes
then log out, login as administrator
to disable:
start>rightclick Computer>manage>users>users>rightclick administrator>properties>General Tab>check"Disabled"
open command prompt as administrator (right click method) and type in this:
net user administrator /active:no
simple, quick, yet effective
Edit: Update
Apparently vista Home doesn't like the method of using the Computer Management and the option is removed, the following command prompt code will work on all versions
CODE
net user Administrator insertpasswordhere /active:yes
make sure to right click and run cmd as administrator

