To answer the question, yes an ordinary avr would work, although I would choose the ones sold on computer stores over those sold at hardwares.

I know you're not keen on using a UPS... but please allow me, for the benefit of those who might be in similar situation as you are...

My suggestions...

1. For a PC yet to be built, why not specify instead a power supply unit which has a multi-volt input capability. For instance, a HEC 550W Win+ Power has a variable input voltage of 100-240VAC and 50-60Hz. You won't even need an external AVR at all whe you have this PSU. What's more if you have plans to upgrade to a better video card (i.e., pci-e ATI Radeon 4870 and below) this psu's power rating and cables can accomodate it.

cons: this type of psu costs around P3k

2: For existing computers, if you add around P1500 to your ordinary avr budget you can get an APC uninterrptible power supply (ups.) My 500W APC at home powers one of my desktops, printer, LCD monitor, SmartBro and router. My other desktop is protected by another brand ups (forgot the brand.)

cons: again, budget. This 500W APC ups cost from P1800 to P2200 depending on computer store.

These ups have saved my data in my two desktops at home during power disturbances several times already. They also isolate my computers from electrical stresses as occurred during power interruptions and transient voltage surges (caused by load switching inside the house.)