Windows XP Activation Query

I have just put a new hard drive in my laptop and installed a fresh copy of XP Pro, as I don’t have my original OEM install disk with me I used one from work.
What will happen if I activate the system now? will that show up at Microsoft HQ against other PCs installed from the same CD?
Would there be any benefit running a repair install from my orignal disk, I recorded the Key before I took the old hard drive out if that is any use.
I’ld rather keep it all legitimate seen as I do own a license for the software.
Where so I stand? thanks