If you are having a message box like this after trying to install windows XP, it is probably as a result of Microsoft having disabled on-line activation of many product keys. If you can't activate your installation within 30 days, Microsoft's product de-activation system kicks in. Your copy of microsoft windows becomes unusable unless you can somehow activate it.
When you buy a desktop or laptop computer with Windows pre-installed, a proportion of the purchase cost has gone to Microsoft. Say around £60 or $100. That money pays for a license for you to use Windows on the machine and is incorporated in the purchase price, much like VAT or sales tax is incorporated in the purchase price. You have paid and bought the right to use the specific version of Microsoft Windows on the computer, and presumably, as far as you were concerned, for perpetuity.
If you have paid that money to Microsoft through having bought a computer with a license, your machine will have a label with a unique number on it. That number is called the product key. If you install Microsoft Windows on a computer, you will normally [1] need to enter the product key in order to finish installation of Microsoft Windows.
After installing microsoft Windows XP, part or all of that product key is sent to Microsoft via the internet. Microsoft then activate your installation of windows. Since May 2005, Microsoft have chosen to stop automatically activating windows installed with many product keys.
If you receive “Message Number 45128” that is probably because either
There is also a Telephone button. If you click the telephone button, you will be given a number to ring Microsoft. If you choose that option, Microsoft should provide a special code for you to re-activate your installation of Windows XP. In my experience, depending on the code, they may give you a new product key to enable you to activate your installation of windows immediately. However before doing so, they may ask you for the part number of the installation media. Mine was locked in a drawer and I didn't have the key to hand, so that was skipped.
Microsoft decided to prevent web activation of Windows XP using product keys which came with many computers, restrospectively, from May 2005. Up until May 2005, automatic internet activation of Windows Xp would work on a single machine/ single motherboard of your choice. Since May 2005, Microsoft have stopped the automatic activation for product keys supplied with computers from some manufacturers. I am aware that most Dell repairers/upgraders are affected and HP/Compaq generally not, but the situation may change at any time. Microsoft say that most users of these computers will be unaffected as their copies of windows will be “pre-activated” Microsoft claim 98% unaffected. Given motherboard failure rate is around 5-10% per year, I guess that over a 6 year period, the number of users affected whether directly or indirectly is likely more than the 2% claimed by Microsoft.
All that being said, if you live outside the European Union, you might not be able to get your windows activated, or get a new product ID at all. I believe there are laws in the EU which give computer users the right to move a software license from one machine to another (but not to use one license simaultaneously on more than one machine).
Some people consider having the right to move software from one machine to another is a scam to make money off US companies. Others may feel uncomfortable with a company who was convicted for monopolistic practises creating obstacles to using software they have purchased perpetual rights to enjoy.
Notes:
[1] If you have a computer/motherboard from a tier 1 manuacturer, and have a windows install disc prepared for the same
manufacturer, the install process might not ask for a product key. If you change the motherboard, it will, and if the product key
is blocked from web activation by Microsoft, putting your license back into use may be tricky.
[ps] Some people believe this problem exists only with activating XP with service pack 2 installed. That is not true. Whether original
or SP2, the same problem exists.