Which UPS

So im buying a UPS in a few days and i want to know which one i should buy. These are the things i need to run on my UPS:

PS3 console


LCD Monitor 22 inch

A modem and a router

Which UPS should i go for? Galaxy has a few UPS listed im not sure which one i should go for.. Any advice ?

Oh and i forgot to mention, I only need like 5 minutes of backup because i have a Generator so when light goes off we have to turn on the generator so the computer then runs on the generator.. I need electricity in between so that my computer doesnt shut down.