Cloud doesn't necessarily help power outages. If you are in an office and the power goes out, the cloud is as useless as your down servers. Now if everybody goes home and then works in the cloud and home hasn't been affected by a power outage that's an option.
That being said, depending on space and needs, $8,000 can buy you a natural gas generator that eliminates the power issue alltogether and is a one time cost versus paying thousands extra per year for ever for cloud.
In addition, shameless plug, just use
www.eversafe-backup.com and that solves the power issue by using the cloud only when needed and you don't to pay for 365 days of cloud when you only need a few days if you have a bad power grid.
Also, internet outages are often more common than power or server failures. If you are in the cluod and have an office, you all are twiddling your thumbs when your internet connection goes down.
Again, take a look at this page
http://www.rackspace.com/cloud/pricing/
Look at 'windows sql standard' that would be your ERP 100 server. Then add in servers for domain controllers, file servers, and any other servers you currently have on premise. Add in bandwidth charges, file backup charges and image backup charges. These prices don't include managed services (they have another page for that and its like 60% higher) so you still need your own IT to manage this stuff. Show me how this over 5 years comes remotely close to inhouse with a virtual server. Heck, show me how in the first year its even competitive. I just don't see the numbers. What am I missing?
You still need a firewall, you still need internet and security, you still need switches, routers hubs, printers, scanners and wifi if you have a physical office. And in most cases, unless you are exclusively using thin terminals, and most want laptops etc, you still need local desktop support