you're probably seeing bluescreen error 0x000007B. What that means is that you don't have the proper mass storage controller driver (basically your hard drive controller) loaded. What probably happened is your motherboard and controller was made after Windows XP SP3, and the driver isn't in windows. to add it, you need to download the driver, put it on a floppy disk or a dvd, then when installing windows in the first part where you see "Press F6 to install additional drivers" you load that driver into windows and then the installation should proceed.
You need to find that driver, and make sure you have the exact one for your hardware. Alternativly, you can adjust your bios configuration so the mass storage controller is in IDE mode, not AHCI or raid, though that limits some of your speed and performance options.
If that sounds difficult, just put windows 7 back on.