You have to install Windows first, then a version of Linux. The reason is because of the boot-loader, which you need GRUB or LILO for Linux, and these will also boot Windows. I ran into an issue with my desktop trying to dual boot. Used partition magic, shortened the hard drive, went to install Mephis, and ended up having to reimage my computer with the latest backup image. I'm not sure what happened. The boot screen would come up, show the OSs, and if I chose Mephis, it would just look at me- no errors or anything. It was strange- I will be trying again soon.