I think most of you are aware that XP SP3 has a new feature that permits you
to install XP without entering a product key. Doing so gives you a 30-day
grace period before being required to enter the pk. Activation requires
entry of the product key at the time of activation if it has not been
previously entered. In effect, this makes your XP SP3 cd a trial copy.
To do a keyless installation, when you install XP and reach the screen where
you are asked to enter the pk, leave the fields blank and click Continue.
To take advantage of this you must be using an XP SP3 integrated cd so you
will need to slipstream XP SP2 and the download from
https://www.microsoft.com/downloads/details.aspx?FamilyID=5b33b5a8-5e76-401f-be08-1e1555d4f3d4&DisplayLang=en
I use nLite for the slipstreaming.
You must do this on an XP x86 machine. Do NOT use Vista.
I have not had occasion to use the rearm command in XP SP3 but it may work
as it does in Vista with a keyless install. The rearm command gives you an
additional 30-day grace period and may be used up to three times. The
command is "slmgr -rearm".
Why you would install keyless is up to you but I use it for experiments in
virtual machines that I only run for a day or two.