I am going to buy my first UPS

Hi all, I have no experience with UPS, so here my questions are. 1) What kind of software should I use with the UPS? I want the PC to log when a power failure happen, and to turn off when the failure lasts too much. That software must work with serial port, as I do not have USB ports. 2) What is RS-232 connector? Is it common serial port? 3) How much sellers lie? I mean, I have seen some low cost UPS and sometimes they can resist longer than high cost UPS. I know that half load of a low cost one is much less than half load of a high cost one, but I do not find that information very trustful. So, guys and girls, how much does your UPS last? 4) What UPS do you have, and how is your life with it? Praise