Drowsy_23051958,
How did you acquire the legitimate license now installed? There are two licenses that consumers may end up with, OEM and full retail.
The license for XP you get with the Genuine Windows Offer WGA Kit is a full retail license for XP.
Unlike an OEM license, which is permanently tied to the computer onto which it is first installed and cannot be moved to another computer, the Full Retail license that comes with the WGA Kit has no such restrictions and can be moved from one computer to another as many times as you want, and will remain valid no matter what hardware changes are made to the computer it is installed on. The Product Activation system monitors hardware changes and if it sees many hardware changes, it may require you to reactivate the installation.
If your situation requires that your specific license be installed many times within a specific time frame, the Product Key will be "flagged" in the Product Activation servers and it may not be accepted for automatic online activation. In such case, you will see a message that your PK has been activated "too many times." If this should happen, simply rerun the Activation Wizard and choose the Telephonic Activation method, and follow the prompts. It should take less than about seven minutes to activate this way.
Of course, as with all Microsoft OS licenses sold to consumers, any one specific license for XP is permitted to be installed and activated on only one computer at a time. If you want to move this license to new computer, it has to be removed from the old computer.