Most of them are used to hold the data for the recovery CD, so users can "restore" their computers to factory conditions.is it a pre-built? i find that a lot of the time there are multiple partitions on my friends pre-built pcs. i dont know why they do it, but if you backup your data and reformat it using the windows xp disc it ought to take care of the problem.
I would check in these places:Its only happened today, thats what makes me think theres the Nero tempory file somewhere. Dont know where though