as someone who rides both, i tend to recommend a set of rollers over a trainer -- especially for fixed gear bikes.

first, trainers are designed for use with quick release skewers and typically don't hold track nuts quite as securely. secondly, if you get a good set of rollers, you can buy a fork stabilizer (you put your bike on it without the front wheel -- it holds the fork in place) which will allow you the total laziness factor that you might want.

also, i find that riding rollers will keep you more alert and will help you learn how to "hold a line" better in normal riding as well as improving your balance. i have no problem riding on my rollers and watching tv, etc.