I want to echo what lighspur1 said about grounding ... the main electrical cause of failure of sensitive (low voltage) equipment in Thailand
is not power surges or fluctuations, it's charge building up on non-grounded (non-earthed) power. If you're using a 2-pin socket, your stuff isn't safe, even with varistors in the way.
Domestic UPS units often only offer failover service, which means they only kick in when there's no mains power. This means such devices offer no protection against surges. If you want UPS consider whether it is for isolation or continued service. It's unlikely to provide the former.
It's also worth noting that a lot of "surge protecting" extension cords only protect the "live" and not the "neutral", which is pretty pointless. If you get a lightning strike it's not going to carefully choose one particular wire and not the other.
Read this:
http://www.thailandguru.com/grounding-e ... rical.html (I have nothing to do with this people, and cannot comment on their services. But their advice is good.)
A.