I'm in the process of reinstalling my whole pc. I have completely formatted C: and left D: (second HDD) as it was with my data on it. I have reinstalled XP and had next to no problems doing that. My first problem was it seemed to install two versions of xp in dual boot. XP media centre (what it should be) and xp pro (i don't own that!). However, i have just turned off the prompt for dual boot on startup and set media centre as my default os, so i'm not too bothered about that. Btw, xp pro came up with an error when i tried to boot from it anyway.

My main problem is that since i have installed xp again i have my two original hdd working plus now another one K: which is completely unformatted and i don't know whether it is a partition of one of the others or not so i don't want to format it to find out because i don't know what that will do :s

Does anyone know how i can get rid of this "new" hard drive?

OK. So sorry. I should have tried before asking. It did turn out to be a partition. I don't know why it appeared though.

Resolution (for anyone interested):

Control panel > Administrative tools > Computer Manager > Disk Manager > right click on the unwanted partition > delete partition

And your done.

Something else that may be useful to anyone else who reads this looking for answers is that, believe it or not, fdisk -l will tell you what physical drive the partition is on. Just thought I'd throw this in for good measure. :-)