Product key is not working??

[Jennifer]

I had to reformat my desktop and each time I put in my product key for XP it
says it is invalid, but I know I am putting in the right number. What do I
need to do?

 

[Shenan Stanley]

I had to reformat my desktop and each time I put in my product key
for XP it says it is invalid, but I know I am putting in the right
number. What do I need to do?

Are you using the CD that came with your computer and the product key that
came either with the CD or is on a sticker on the computer itself?

 

[DL]

Where are you getting the key from?
Are you missreading 0 for O or 8 for B etc?