I've got to say, i'm on Telewest/NTL/Virgin and have been for about 5 years. I can't really say that i've had any downtime that wasn't caused by a dodgy router.
I had a Netgear that i absolutely detested - give it some bittorrent, and the wireless crashed after about 5 minutes, although it never had a problem if you did it through the wired network.
Weirdly, it took me about 2-3 years to replace it