UPS requirements for mid-high vid editing system

Hi all,

I prefer desktops over laptops for vid editing, but work in an environment where power outages are routine.

The new system I am building will be used for a mix of video editing and gaming as well.

I am looking at (core components)

Proc: i7 2600k or i5 2500k (with overclocking but within the limitations of air cooling, not water)
RAM: 4 x 4 gb (16 gb total)
HDD's: 2 or 3 SATA (cant afford SSD just yet)
Gfx: nVIDIA 560 ti (with 448 CUDA cores) or vanilla 560 ti
2 LCD monitors (1 of them on UPS backup)

Now, 'eXtreme PSU calculator lite' puts the voltage requirement of the OC'd i7 2600k version of this setup to around 427W.

>I'd like to know what PSU should I go with? (would prefer something economical)

And,

most importantly, what kind of modded UPS can keep this rig running for an hour on car (wet cell) batteries and how much power would I need?

I hate the fact that Intel have put in the IGP HD3000 in these procs but do not let us have Optimus tech for desktops, as I know that the gfx card will be the most power hungry component of this system. Is there any way to work out a way around this?

Also considering an cheap xeon (basically locked yet much cheaper i7 2600 as well) in case power requirements for the OC'd system are too high. (has no onboard gfx as well, which I do not need)

http://www.newegg.com/Product/Prod [...] llFullInfo

I am open to suggestions. In case the running cost of this gets too high, I am even considering a Lenovo W520 laptop (i7 2760 QM, Quadro 1000M = $1300) as an alternative. But would just like to first exhaust all desktop possibilities.

Thanks in advance!