This is just a work around I found because of the way windows tracks activation on vista and 7.
If say your motherboard goes out and you have to replace it or you upgrade your ram windows will ask to reactivate.
what its actually doing is telling microsoft you installed windows on a second computer wich means the third time around you violate your license and need a new key.
But!
instead of buying a new key when it says it is unable to activate.
It will either say activate by phone or show me other ways to activate(as in the image below) depending on how you went about activating.
it gives you a window with an area selection. pick your country or the one closest to you and give them a ring.
These calls are toll free (and note the little computer landy cant unserstand you if your really mad)
If you have issues with speaking to her heres some tips
you can type the numbers she asks for.
1 is repeat
2 is continue
0 is help
She will then ask you how many computers vista/7 is installed on.
Tell her one and they will reset your computer count and give you a new key to activate windows with.
**post modified by ñòóKýçrÕôK as we are not here to give people incentive or motivation on how to cheat or "get by" very specific and well defined legal use guidelines on copyrited products**