Microsoft repair question

ok, so, my grandmothers computer decided to bite the bullet. So, i put together a new one for her. I tried putting in her old HDD and running windows repair (XP). After the repair is done, i get a popup telling me i have to activate windows before i can login, and if i want to now. I can't activate it since there are no drivers installed. Is there any other way i can get this done?

Activation can be done over the phone. That's your best bet. Make sure you tell them that you rebuilt the computer, not made a totally new one.

Also, blame Windows for crashing and you're pissed off about having to call. Otherwise, they'll make you explain why you're activating Windows... annoying.

And that should work even though i cant get past the welcome screen?

If you went beyond the activation time and it is forcing you to activate the computer without giving you a chance to install anything, yes. Phone activation is an option.