I just bought a trainer in November -- CycleOps Magneto.

I was looking at Fluid trainers because they offer the best resistance, however to get one that REALLY works well and doesn't leak, you need to spend $300++, and then the resistance can be SO HARD that it is difficult to turn the pedals.

Basic magnetic trainers are good for occassional work-outs but beware that the longer you use one, the hotter the magnets get, and the more prone they are to skipping -- affecting your ride quality. Also, resistance is not as high with basic magnetic trainers.

The CycleOps Magneto is a good balance between Fluid and Magnetic -- kind of best of both worlds for around $200. You may want to do search for CycleOps and read about their trainers. Other good brands: Kinetic, Blackburn