Windows Network Load Balance for fail-over to backup web server

I know Windows NLB is for load balancing across servers, but I need just fail-over. I have a primary web server and a backup. I add both to the NLB cluster and then pause the backup host. All traffic is handled by the primary. If the primary goes offline either scheduled or unexpectedly, via script I un-pause the backup host and now traffic flows to the backup. Make sense? Bad idea? Really bad idea? Alternatives?

Thanks!