Boot into safe mode, and if that works right click My Computer and go to Propteries. Under Advanced or somewhere there, there's an Error & Recovery Section and you must untick the box to automatically reboot when BSOD occurs. Then boot normally and it shouldn't reboot when you BSOD and you can Google the error code. Or you could record the booting of your machine then pause the video the moment you see the BSOD, or take a picture really fast.
Also inside of 7, right click Computer and select Manage, then go to Disk Management. You should see your Windows XP partition and you can assign it a drive letter. After you do so, browse Computer and your Windows XP drive and make sure you can see your Windows and sub-directories/files.