?? help with bootcamp windows7 upgrade

I'm new to mac ownership and I have set up Bootcamp on my Mac Book Pro (OS 10.6.4). I have a full version of Windows XP SP3 and an upgrade disc for windows7. My inention was to install XP then upgrade it to windows7. However, my XP disk was not recognised (does it have to be SP2?) but, strangely the Window7 upgrade disk was accepted and used to make a clean install. Predictably, I am now getting error messages to say that I have not got a valid licence for Window7 as it is an upgrade only version.

Does anyone have any ideas about the simplest way of solving this? (short of just buying a full version of Windows7 for the activation code)

thanks

Just install Windows 7 again on top of itself and it will validate. Or, follow the instructions given at this site.

Note: For others reading this thread. The OP has a valid licensed copy of XP which means he meets the upgrade criteria for Windows 7. The above link is not meant to be used by someone who does not meet the requirements. Please refer to the MS EULA regarding this.

thanks for your help. Great tip - it worked perfectly