Bicycle Trainers and Winter Withdrawal

[1884 trainer, image via Wikipedia]

I am curious to know how many of you out there use bicycle trainers. I am now seriously considering one, as my winter roadcycling situation is truly dire. The frequent snow is making it impossible to plan rides, and all the muscle tone I'd built up over the Spring, Summer and Fall is slowly but surely disappearing. I am starting to feel lethargic and out of shape. There is a lot of pining going on - and it's only the start of January!

Bicycle trainers are a new concept for me and I have no idea what to expect. To what extent does being on one resemble actual cycling? Can they be used with fixed gear bikes? Is fluid necessarily better than magnetic? I don't want rollers, I don't want the trainer to be noisy, and I don't want anything overly complicated - but otherwise I have no idea.  Please chime in, and no doubt your comments will be useful to others who are considering this as well. A trainer cannot replace the thrilling experience of riding a roadbike on the open road, but it can at least help me stay in shape while still interacting with my own bicycle. It's going to be a long winter...