I'm suffering from this at the moment...
My ISP is Zen and I've tried two different netgear routers - both of which contain this chip and I suffer from CRIPPLINGLY frequent cutouts with the ADSL and the speed is VERY slow.
But is it the ISP or the chip-set!? I don't really want to buy another modem/router if it isn't that (unsurprisingly...) and *all* of my mates have netgear routers :(