I would start by removing the new hard drive to see if you can get the computer to boot again. If you can then you can check the Event Viewer for any error details to try and narrow down why it doesn't like the new drive.
Then you can prevent the computer from automatically restarting on the blue screen error by going to System in Control Panel and go to Advanced System Settings. Then click on the Advanced tab and then the Startup and Recovery Settings button and uncheck the box that says Automatically restart. The next time you reboot, it should stop on the Blue Screen so you can read what it says.