doesn't XP SP1 or SP2 sync up OS with hardware? Thought I read somewhere that one of those SP does that. In other words, if you installed a legal copy of XP with a specific serial key, that serial key is only going to work with that pc's hardware. So, if you reformat that pc without any hardware changes, you'd be fine. However, any hardware change (in this case - motherboard) would require a reformat and new key (obtaining a new key probably means a call into Microsoft). Or is it only for hard drives? I'm not sure, but I thought it was the entire hardware profile.
For me ... I dont have this problem, because I install XP Pro with a cd that does not include any service packs, then add SP2 later.