The "5 times rumor mill" is over! If you have to reinstall XP or even Vista at this point the new activation is much easier since MS wants you to have a valid copy running on your machine. It used to take a longer period of time for reactivation or calling MS directly to read a number the operator then asked for after having you follow instructions to enter a command. It's also been made easier to acquire new licenses that allow use on multiple systems since that's what MS wants to see.
They would rather see you valid and reactivated then running otherwise even with an OEM release. For multiple systems running the same disk you would need a retail copy there however. Keep this in mind. Since people upgrade faster then they can reactivate MS now has the validation tool when going for updates to vierify things like having a valid installation. http://www.microsoft.com/genuine/downloads/whyValidate.aspx