How long will a router last, on average?

We bought our router in Future Shop and according to the guy who recommended the unit it was top of the line (almost four years ago). It seemed to work very well in the first three years but recently we have been having some issues with disconnection. Last month was really bad, it disconnected between 5 and 15 times every day and it just annoyed the hell out of me.

I called Shaw and the guy said it could be our router or the connecting cables being old. They sent a tech guy to our house to replace the cables and things became a bit better. But we still get disconnected 3 - 5 times every day. The connection could be gone for just 5 minutes or up to a couple of hours. No matter what I do it will stay disconnected until it comes back on its own. What baffles me is that when we lose wifi connection our desktop (wire connection) is also affected. I asked the tech guy but he insisted it was not Shaw but something in our house.

How long, on average, a router should last? I don't mind buying a new router if it is indeed the source of the problem. I just don't understand why I can't access the Internet using my desktop if the router is the culprit.

If we are going to buy a new one which one would you recommend?