|At what point does it stop booting? If it it just won't boot at all then you have a hardware issue which is probably what caused the failure of the program to install.|
If it starts to boot into Windows and either hangs, blue-screens, or restarts then when you restart it again, tap F8 a few times to get the safe mode menu. then try (1) (Last known good configuration; (2) Safe Mode (then do a System Restore to a time prior to the problem); or (3) 'Repair My Computer' - choose the 'repair' option on the 'Install Now' screen and let the system try & repair the problem, otherwise, again, use System Restore.
"I've always been mad, I know I've been mad, like the most of us..." Pink Floyd