buffer underruns with dvgrab - How to prevent

Greetings, I am getting buffer underruns pulling digital video from my camera. What changes could I make to the cache to improve the throughput. I am using "dvgrab --timestamp --format dv2 filename" I have a Athlon 1800 with 1gb of memory and I am using my faster 40gb hard drive. Any input on this would be welcome! Thanks in advance, Doug