See above mate, apparantly MS have stopped retailers supplying an XP CD on PC's where it is pre-loaded.
Thanks for the replies guys, however I'm still confused.... I know that my slave drive will be fine, but I don't want to lose the data on my primary drive with the OS on it unless it's 100% necessary.
Once I've replaced the MB I will have no XP CD, only the master CD's I created when I first powered it on. Will I be able to reinstall XP from these with a different MB to the one I had to start with?
As for the suggestions of "install XP pro" etc, that's a good idea, but I don't want to get into A: buying a legal copy, or B: Going illegal, when I've bought a perfectly legit PC with XP installed.
By not supplying me with an original XP home CD, it seems to me like I'm actually being encouraged to beg / borrow / steal an illegal copy of Windows, just to get up and running again!