I have a 98 4cyl accord and the cat just went like 3 months ago and luckily I was able to replace it under warranty. (even though my car is not under any dealer waranty)

All cats are supposedly covered till 80,000 miles (regardless of dealer warranty)....so if you have less than 80k on the clock you can get your cat and O2 sensor replaced for free from Honda as I did. Dunno if this info is relevant to your case, just thought I'd pass on the info.