Yah, any UPS will do the job more or less. What you want to do is think about how much run time you want and select the batteries with that in mind. Check the electrical specs on the TV that you have in mind and calculate what your needs are going to be. Also, keep in mind that different sets have different power requirements. A huge CRT will draw quite a bit more power than a smaller LCD screen will.
Well to be honest it is more important to keep the PC up and running rather than the tv but in this case the monitor for the HTPC is the tv...so... in order to work the computer you need a monitor. I've seen this done several times but if it is completely retarded to do then I won't try it anymore but why not... if I got a power failure then presto I'm still watching episodes on file...
I actually don't even have cable tv so the sole purpose of this is for replay of files.... so tv isn't all mighty in my life... I just enjoy watching the occasional file on the bigger screen... also I know that this UPS acts as a filter as well and I don't know all of the mechanics of it or if the electricity even needs to be filtered but if someone could enlighten me then I'd be glad to learn...