http://www.apc.com/tools/ups_selector/index.cfm?

try the ups selection tools that apc has on their site.
if you look under the telecom (middle colum) it says by load fill it out and viola! it helps you select one.

i have (2) 1500kva ones that i can use if need be but most of my stuff is set on/off cept for the incubator