+1 For Dwarfie!
If your system has shut down like this maybe once, you may or may not have got away with it. Repeated shutdowns like that, will definitely cause corruption and damge of your files. Invest in a UPS my friend. We get occasional power outages here in rural Lincolnshire (thank you, Wind Farms!) so I fitted really good, effective Surge Protection.
If and when it blows the Surge Protect part, (it is visible if it does) I will buy new. If the outages get worse, I will buy a UPS.
You don't give your location, but here in the UK I am talking about something like this: APC Back-UPS ES 700 UPS - AC 230V / 405W / 700VA / 8.. | Ebuyer.com
There are others, from other outlets, this is just an example, if you have a large Network, but this is one of the lowest-priced, does a good enough job for a small network, or just one or two machines.