Hey Carlos,
I've been buying (and relying on) UPS's for years and after many experiences with different vendors I've come to trust only one brand, APC. I'll warn you now, they're not cheap.
A few other tips to think about...
Size Matters
When sizing your UPS device be sure to consider more than just your computer. Think about all of the critical devices between you and your broker. You've got your computer, probably the router, an internet modem of some sort, multiple monitors, etc. You'll want to be able to put all of those items onto the UPS. The goal is to survive a power outage, or even an momentary brownout, with no impact to your trading desk. Most ISP's bring your internet service into your residence over fiber, CAT6, coaxial cable, or phone lines, and as long as your on-premise equipment (the modem) is protected by an UPS, your internet connection will actually continue to operate just fine while your residence is completely powered down and in the dark. Next is your router or switch. Then your computer and monitors. Get all of those things onto a strip or two that is then plugged into the UPS. It does you no good if your computer is up, but your monitors are not, or your internet modem is dead.
Time Matters
Depending on the model of UPS you pick, you'll have varying levels of time before it's power reserve runs out. At the low end you should have no less than 15-20 minutes, on the high end some UPSs will give you hours. Either way, you'll still be in control and have time to either exit your positions or stay in the market. The amount of money you spend on an UPS will largely be dictated by this decision alone, how much time do you need to have in reserves. If you only need 15-20 minutes you can get by with a less expensive model. If you require all-day trading, then it's going to cost you, potentially in the thousands.
Have a flashlight at your trading desk, cause the only light you'll have is whatever your monitors are putting off. Those of you with black backgrounds will have less light than those of you with white backgrounds (naturally).
Simulate an outage until it doesn't phase your nerves
Once you're all setup, I recommend doing several live tests. Not in your live account of course, but in your simulator account. Have someone randomly shut off the breaker to the circuit feeding your UPS and measure how much time you have with all critical devices plugged in. You're going to need to remember this number. Establish and practice your emergency procedure for exiting positions and taking your accounts flat. Most UPSs throw an audible alarm when power goes out. It can be a very nerve racking experience, even for the most emotionally stable trader. So, in a controlled fashion, when your money is not at risk, simulate an outage and practice your response procedure(s) over and over until it doesn't phase your nerves at all. "Oh, I just lost power, ok, I need to do X, Y, and Z." Cool as a cucumber. The reason this is very important is because in the heat of the moment you need a cool head to be able to focus all your attention on exiting your positions. If your freaking out about the room being dark, or the UPS alarm squawking in your ear, you're at risk for making bad decisions.
It is a really weird feeling when you lose power unexpectedly, your entire house (or neighborhood) is dark, the lights are off in your office, it might be pitch dark, the UPS is the only sound squawking loudly, but meanwhile your ISP modem, router, computer, monitors, trading platform, etc. are still lit up and operating like nothing happened. Prepare yourself for this and practice it regularly so when it does happen you brush it off and keep your cool.
I couldn't fathom what it would be like to be in a heavy position and everything just goes black. Traders worst nightmare.
best of luck,
Uncle B