1. Open the Start Menu.
2. In the white line (Start Search) area, type
slui.exe 4 and press
Enter.
3. Select your nearest location and click on the
Next button. (See screenshot below)
4. Click on
Continue in the UAC prompt.
5. A local phone number should apear with a set of numbers generated by Windows and displayed on your screen under
Step 2: . (See screenshot below)
NOTE: There will be sets of numbers under the 1 to 9. I just removed them here for obvious reasons.
6. Call the activation phone number selected.
7. At first, the activation line will be automated, so you will be asked to enter or speak the numbers (Step 2 in screenshot below step 10) displayed on your screen into the phone.
8. If Automated Service is Successful NOTE: Usually this is not always successful.
A) The automated service will issue you a set of Confirmation ID numbers.
NOTE: Have a pen and paper handy to write these numbers down.
B) Go to step 10.
9. If Automated Service is Unsuccessful A) If the activation service informs you that it was unsuccessful and cannot help you with activation, then STAY ON THE LINE and your call will be transferred to an activation operator who will assist you in activating your copy of Vista. The operator will give you the set of Confirmation ID numbers if they agree your copy of Vista is legitimate.
NOTE: Just explain to the operator your situation and what you did to require activation. (EX: hardware upgrade, installed Vista on a new computer after uninstalling it from the old one, etc...)
10. Type in the set of Confirmarion ID numbers given to you into the
Step 3: area to be able to activate Vista. (See screenshot below)
NOTE: You will get these numbers from the phone automated system or operator after they have confirmed the numbers you gave them in step 7 above.
NOTE: The numbers in Step 2 of this screenshot will be there for you to use in step 5 above. I have just cleared them from this screenshot for obvious reasons. 
11. When you get the
Activation was successful window, click on
Close to finish. (See screenshot below)