One question-there is a switch on the back-should I leave it switched on or switch it off when I shut PC down?
This was one of my concerns, but I have no switch, and it would mean either disconnecting the router by the adapter plug, or crawling under the PC to reach the mains board. If left on 24/7, it must use a certain amount of electricity. Even if the cost is only 1p per hour, this is still about £7.20 per month - if your ISP suddenly put their price up by that amount, for the same service, would you accept it?
At the moment, I do leave mine on, but only because I haven't got round to testing the second PSU connection on my PC, to see if it's permanently live. If it goes on and off with the PC, I was thinking of exchanging the 13amp plug on a short extension lead, for a euro (kettle plug) connector, and using the PSU on my PC to power the router. I'm still also uncertain, however, if the PSU would be adequate to power the router, and how the existing transformer for the router would fit into the picture, and I'm a bit concerned about buggering something up by trying it.