Oh BOLL##KS need some more help gents I have just changed the RAM module and now there is a Windows product activation window,

it says: since Windows was first activated on this computor the hardware has changed significantly.
Due to thease changes windows must be reactivated within 3 days.

It asked me if I wanted to activate now or remind me later, so not knowing what the F##K it was I clicked remind me later hoping that it would let me carry on as normal but it does'nt it just keeps shutting down.
so I have now clicked on "activate" and it is giving me 3 options:

1, activate windows over the internet
2, I want to telephone a customer representative to activate windows
3, remind me to activate every few days

Any help lads please on what it's all about