I've used a Cycleops fluid trainer, a Computrainer, and rollers, but my favorite by far is the Wahoo Kickr. I realize it's not cheap, but it's worth it. Combine the Wahoo Kickr with Trainer Road and some Sufferfest videos, and you can do some really good, specific training. I do almost all of my mid-week training this way, all year long. Also, if you're looking at rollers, check out the Trutrainer rollers. They are very well made and have a flywheel in one of the rear drums, which creates resistance. If you are concerned about falling on rollers, you can try riding in a doorway.