So, I used some magic tools that my flatmate has, and it turns out that Ghost had decided to set it's shitty little 7MB partition as the system partion. Which meant that my C drive wasn't the system drive any more. Deleting the partition caused "Cannot find NTLDR. Press Ctrl+Alt+Del to restart" at Windows boot. No partitions were set as system partitions, so my PC was picking the first partion on the first hard drive and trying to boot from that. Finally, I managed to change the boot disk priority in the BIOS and my PC now boots.
So I'm now setting fire to my Ghost CD...