Battery Backup System for iMac

I'm looking for a good UPS for my iMacs. I need one for an iMac G4 15" 800Mhz, and an iMac G5 20" 2.1GHz with built-in iSight. They are both in different locations so I will need to buy one for each. I will only be using the UPS to plug in the computers and nothing else. I just need a battery backup system so I will have time to turn my computers off, in the event of a power failure. I rarely ever leave them unattended and always turn them off when i'm done using them so auto shutdown software compatibility isn't really a conern. I just need a Backup Battery System. Particularly, i'm looking for an APC UPS. Can anyone recommend a good model? Also, does anybody know how much the theoritical maximum power draw for each of the aforementioned iMacs? I think the iMac G5 20" has a theoretical maximum of 180watts but I'm not sure. Can anyone confirm this?

I have 2 APC "Office 280" models. One is for an iMac Rev D and the other is on an eMac. I use them for exactly what you want, time to save and shutdown gracefully. They have six sockets; 2 are protected by the UPS (total of 280 watts, hence the name), the others are surge protected only. You get (I think) 9 minutes of battery power. The newer one has a USB socket for shutdown software that works with OS X. They are also self-testing and will beep if the battery is no longer good. The older is 8 years old, the newer 5. Both have performed the way they are supposed to and I've never had a problem with either.
According to Apple the power draw for the G4 iMac 15" is 130 watts and the G5 20" is 180.