I have a problem that I can't seem to RESOLVE.  I inherited my Dad's computer after he died.  BTW.....he never used it.  After some time, my whole system crashed & I had to re-install everything.  There was no disc for Windows XP, so maybe it came already installed, I don't know & obviously can't ask.  Anyway......my nephew gave me his copy of Windows XP to install, as he was no longer using it.  He went to Vista, so no longer needed it.  Well............after a short while, I'm continually getting all these messages that my copy of Windows is not genuine/valid & so I can't get updates etc.  Tried calling Microsoft & can't seem to talk with a REAL live person!  This is DRIVING me nuts!  I'm basically a computer idiot & have a dial up connection, so searching for an answer is going so s-l-o-w!  Can anyone help???  I had this problem a 2 years ago, I got an engineer and he reinstalled XP, but I think there should be some other way, I was not much of help.Can you give us the make and model of your computer, please?What # did you call for Microsoft ? ?I'm sure that I'm not doing this correctly, but I'm trying to respond to the 2 posts that replied to my question.
1) To Patio: The first # I called was 1-866-242-4609 in which I was told to call 1-800-936-5700.  I've also called 1-866-234-6020

2) To Saviour: My computer is a HP pavilion v50.If your father's computer is recent enough...it probably came with the operating system already in it...in a partition specifically for the purpose of recovery.

When you turn the computer on, you should notice it...it will read something like "F11 Recovery".  I'm not quite sure what function key it is, but you should be able to get more info from the HP site.

Also, v50 is the monitor model number...not the model number of the Pavillion.By the way, here's the link for PERFORMING a recovery on your Pavilion desktop...

HP and Compaq Desktop PCs -  Performing an HP System Recovery in Windows XP

Pay close attention to the SECTION "RECOVERING During Startup".I think, it's F10 with XP, and F11 with Vista installed.