and as ever, be careful when testing.
So I decided to test my setup -
now note, I am pushing it with what I have connected to this poor little 650VA - two monitors, laptop (without battery and attached 1TB 2.5 inch), tower box (GTX550Ti, 3 internal hard drives), external hard drive, desk lamp, adsl router, small switch, hands free headset, external speaker setup (2.1), handsfree telephone, headphone amp,

ryobi cordless drill battery charging

, powered USB 3 port extender.
So, flicked the switch and waited - 3 minutes later, out for the count - pretty much as expected
What was unexpected was when everything came back up again my wireless was, quite frankly, screwed! Everything looked fine in the settings but the repeaters weren't picking up properly - let's just say I had a very unhappy family. Reboot router, switch off, blah blah all the normal stuff.
Eish
Temp fix, fire up the 3G Hotspot, wife happily surfing again - phew - pain averted for the evening. No time to search for fix, so off to bed. Next morning, first thing off to Uniterm (for a 'just in case it's poked' replacement)
Then the search for a fix begins - eventually stumble upon a possible solution - switch off ADSL Router/Wifi for 20 - 40 minutes - apparently clears some doodad inside - get home, decide to go for overkill and leave off overnight - it works!
So, if anyone experiences flaky Wifi after a short power outage, try leaving your router off for 20-40 minutes before you go rushing out to buy another.