I went from rollers to a trainer. Rollers are good for simple tempo spinning sessions - ie. just spin to the TV for an hour. I get a much better workout and the time goes much faster on my trainer doing an interval workout. I usually use Spinervals DVD's, etc..

For example, I only had 30 minutes to ride this morning so I did a 1/2 hr Spinervals Time Saver workout - warmup followed by seven 90 second max effort intervals with 90 seconds rest followed by one 3 minute max effort. I was worn out after 30 min with a great workout on my Powertap file. This was much more valuable than a 1 hour tempo spin on my rollers. I would never go back to rollers.

By the way, don't buy a cheap trainer - total waste of money.