In theory, yes there is a way. Make a boot CD that has everything you need and never get in a situation that you need to save anything, no documents, no saved bookmarks, no downloaded files. Basically a computer that's being used as an interactive television, entertainment only, and nothing remembered. Then sure, you probably could.
Personally, I really need a hard drive, and loss of power is really hard on those, they just don't like dropping the heads on the moving platters very much. And I like saving bookmarks so I don't have to remember all of the sites is find on the internet, plus it's kind of good to have those cookies that remember for me where I left of the last time I was on that site.
There's another plus to some UPS devices. Some of them (yes, they're more expensive) also filter the electricity. You computer won't get those little spikes and sags that it can mostly handle. Cleaner electricity also means running with out little voltage changes. Doesn't seem like much up front, because most modern power supplies can handle small changes in the input power, but why work a device to it's limits, use something that's designed to handle problems like that and extend the life of that power supply (and the rest of the components in the system - they all take the hit).
I guess the real answer is, if you are ok with replacing some hardware from time to time, and you don't mind loosing what you're doing at the time (even that 4 hour download at the 3 hour 45 minute mark), then, no an UPS is not really necessary.
Edit: I caught a couple of spelling errors, bet you can catch more!
Last edited by chuckbuhler; 11-03-2007 at 12:11 AM.