I'm seriously considering buying a trainer, so I can get some more cycling into my rotation during the winter months - I rode last week for the first time in a couple of months, and it hurt!

That said, I'm a broke grad student. I've looked for used trainers, and will continue to do so (though I've had no luck so far) - but I'm tempted by the "Ascent Adjustable Magnetic Trainer," which Performance now has on sale for $89. Anyone have experience? More generally, what's the difference between a magnetic and fluid trainer? I'm only an amateur road cyclist so my body isn't a fine-tuned machine or anything - but I don't want anything that might damage my bike!