This is my first year doing the lights, My old laptop 1.6G Pentium M with 512 meg ram is doing great. The first night I was a bit upset that my laptop rebooted and the show didn't go off. Found out that window did an update and rebooted.
Short story.
Turn off automatic update, virus scanners, and any other "automatic updating software."
If possible disconnect your show computer from the internet.
Turn power management to "Always On" system standby and system hibernate to never.
If using a laptop make sure closing the lid doesn't shut down the computer.
Also I find a laptop to be a little more convenient smaller, portable, built in battery backup.
Just my 2 cents