I ordered a Rack UPS for a Sunfire X2100 M2. They are supposed to only pull 250W. The APC is rated much higher. The only other hardware in the rack is a switch. I'm thinking it will last an hour. Thoughts? Oh, http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SUA1500RM2U&tab=compare A Sunfire pulls about 300W. This thing is rated for 1440VA, and 27 minutes at half load. I'm thinking I'll get well over an hour?